Chapter 4-5: Adaptive Strategies - Bryophyte Ecology

CHAPTER 4-5 

ADAPTIVE STRATEGIES: 

GROWTH AND LIFE FORMS 

Figure 1. Hypnodendron menziesii demonstrating the clonal growth and dendroid growth form that is possible in a humid climate 

such as that in New Zealand. Photo by Jan-Peter Frahm. 

Growth Forms and Life Forms 

Bates (1998) concluded that life form is a useful 

concept in bryophyte ecology because of the "exceptionally 

high dependence of bryophytes on transient external water 

supplies." He points out that for bryophytes it is not the 

individual that forms the ecological unit, but rather the 

clonal or colonial life form (Figure 1). The life form is so 

constructed as to minimize evaporative loss while 

maximizing photosynthetic light capture. In the Taymyr 

Peninsula, Siberia, differences in life form can reduce 

evaporative rate by 5.3-46 times, depending on the species 

and site conditions (Vilde 1991). 

Definitions 

Meusel (1935) describes growth form as the overall 

character of a plant and explains it can only be determined 

by detailed morphological analysis. It is a purely 

morphological term, as opposed to life form, which is more 

encompassing and describes the result of life conditions, 

including growth form, influence of environment, and 

assemblage of individuals (Warming 1896; Mägdefrau 

1982). Life form embodies all the selection pressures that 

are brought to bear upon a species, or in the words of 

Mägdefrau (1969), "the organization of a plant in 

correspondence with its life conditions." 

If these life forms persist genetically, we tend to 

assume they have adaptive significance. Gould and 

Lewontin (1979) and Mishler (1988) warn us of the trap of 

this type of thinking. We must recall that selection works 

against those things that are not beneficial, and that it is a 

slow process, even slower for those things that convey only 

a slight disadvantage. Furthermore, such characteristics as 

life forms may simply carry an occasional advantage, an 

occasional disadvantage, or little difference from another 

life form. Correlation of life form with habitat, however, 

can be used as supporting evidence for the adaptive value 

of a given life form. 

37

38 Chapter 4-5: Adaptive Strategies: Growth and Life Forms 

Early classification of life forms had little relevance 

for bryophytes. Dansereau (1957, in Ricklefs 1990) 

classified plant life forms into trees, shrubs, herbs, 

epiphytes, lianas (vines), deciduous, evergreen, and 

bryoids. Raunkiaer (1934) relied primarily on winter 

characteristics and based his system on bud position: 

phanerophytes (phanero = visible) – tips of branches; 

moist, warm environments 

chamaephytes (chamae = dwarf) – shrubs and herbs, buds 

near soil; cool, dry climates 

hemicryptophytes (hemicrypto = half hidden) – die back 

to ground in winter; cold, moist 

cryptophytes (crypto = hidden) – buds buried by soil; cold, 

moist 

therophytes (thero = summer) – seeds; deserts, grassland 

Jargon of Life History 

First, perhaps it is necessary to distinguish between life 

history (or life cycle) traits and life forms. As During 

(1979) points out, holomorphy (total form, Hennig 1966; 

the German Gestalt) of plants resulting from their 

adaptations to their environments certainly relates to their 

strategies. However, the life strategy refers to life cycle 

characteristics and their timing (treated in the next chapter), 

whereas life form refers to the morphological characters of 

individuals as well. La Farge-England (1996) points out 

the inconsistencies in the literature regarding the term life 

form and supports Barkman (1979) by defining it as "the 

overall organization of growth form, branching pattern, 

general assemblage of individuals, and modification of a 

population by the environment." Growth form, she 

reminds us, is "the structural architecture of the individual 

moss plant." But such architectures can be modified by the 

environment, hence merging life form and growth form 

(Tangney 1998). It would seem simpler to define one as 

the genetically programmed form and one as the 

environmentally modified form, but the muddle in the 

literature has crossed those lines with both terms. Thus, 

even with the foregoing definitions, confusion in the use of 

terms will still be with us and I shall make little attempt to 

unravel their use in the literature presented here. 

Therefore, interpretation of their use should be done with 

caution. 

Growth Forms 

Since growth form is the simpler result of genetics, we 

should examine that first. As La Farge-England (1996) 

stated, the terminology of growth form, branching pattern, 

and position of perichaetia have been used inconsistently in 

the literature. This morass of literature makes it difficult to 

compare studies and to sort out the real meanings in 

nomenclature. After an extensive review of the literature 

and usage of the terminology, she recommended the 

following interpretations: 

1. Growth form is distinct from life form. 

2. Direction of growth does not necessarily imply 

perichaetial position; some acrocarpous mosses 

(having terminal perichaetia) grow horizontally, 

whereas some pleurocarpous ones (having 

perichaetia in lateral buds or on short side branches) 

grow erect. 

3. Cladocarpy (Figure 2) is distinct from pleurocarpy, 

with perichaetia terminal on lateral branches and with 

juvenile leaf development similar to that on vegetative 

branches; perichaetial branches have lateral primordia 

that potentially develop subperichaetial branches. (It 

is defined in Glossarium Polyglottum Bryologiae as a 

type of pleurocarpy having sporophytes borne 

terminally on short lateral branches, as in Fontinalis). 

4. Pleurocarpy is defined as having perichaetia terminal 

on lateral innovations that appear sessile and swollen 

along supporting axes. Juvenile leaves are 

morphologically different from those of vegetative 

branches. Perichaetial innovations lack lateral branch 

primordia and thus do not produce subperichaetial 

branches. Pleurocarpy is restricted to Hypnales, 

Hookeriales, and Leucodontales, including 

Spiridentaceae and Racopilaceae. 

Figure 2. Cladocarpous branches of Macromitrium 

microstomum. Photo by Janice Glime. 

But traditionally, growth forms of mosses have been 

divided into those that are acrocarpous (Figure 3) and 

stand vertically (orthotropic mosses) and those that are 

pleurocarpous and lie horizontally relative to the substrate 

(plagiotropic mosses; Figure 4) (Meusel 1935). This of 

course leaves a few out of the scheme, as noted by La 

Farge-England. The orthotropic mosses can be further 

divided into the protonema mosses (Figure 5), with short 

or non-existent shoots that wither after the sporophyte is 

produced, and turf mosses, with upright shoots that bear 

new shoots after the sporophyte forms and subsequently 

bear further archegonia and more sporophytes; these new 

growths are the innovations. The plagiotropic mosses 

(Figure 4) include thread mosses (e.g. Leskeaceae, some 

Amblystegiaceae), with little difference between the main 

stem and lateral branches, the comb mosses (e.g. 

Hypnaceae, Brachytheciaceae, Meteoriaceae), with a strong 

main shoot with many simple or branched lateral branches, 

and the creeping-shoot mosses (e.g. Leucodon, Antitrichia, 

Climaciaceae, Hypnodendraceae), with rhizomatous main 

shoots that give rise to upright main shoots. 

Figure 3. Acrocarpous growth form exhibited by 

Oncophorus wahlenbergii. Photo by Michael Lüth.

Chapter 4-5: Adaptive Strategies: Growth and Life Forms 39 

Figure 4. Plagiotropic, pleurocarpous, perennial mosses. a & b. creeping shoot mosses – Antitrichia curtipendula. c. creeping 

shoot moss – Climacium dendroides. d. creeping shoot moss – Leucodon brachypus var. andrewsianus. e. thread moss – 

Amblystegium serpens. f. thread moss – Leskea polycarpa. g. comb moss –Brachythecium reflexum. h. comb moss – Hypnum 

sauteri. a, b, e-g photos by Michael Lüth; c, d photos by Janice Glime.


Figure 5. Protonema mosses. Upper: Pogonatum aloides. 

Lower: Buxbaumia aphylla. Photos by Michael Lüth. 

The same species may exhibit more than one growth 

form. For example, in some populations Hylocomium 

splendens (Figure 6) exhibits monopodial growth (single 

central axis with apical growth) (Ross et al. 1998, 2001). 

However, some populations can continue by sympodial 

growth (growth produced by lateral buds just behind apex). 

In forest habitats of temperate to mid-arctic regions the 

growth is primarily sympodial, creating the stair-step form 

that easily delineates annual growth (Ross et al. 2001). 

Higher nutrient availability promoted sympodial growth. 

In tundra and high arctic habitats, monopodial growth 

predominates and increments cannot easily be discerned. 

Transplant experiments demonstrated that these traits were 

plastic, but that natural variability was greater among those 

shoots in natural populations at transplant sites, indicating a 

genetic component as well as an environmental component 

to the differences, affecting both growth and life forms. 

Figure 6. Weft life form of Hylocomium splendens. Photo 

by Michael Lüth. 

Ross et al. (1998) found that the sympodial 

Hylocomium splendens plants had increasing stiffness with 

stem segment age and flexibility decreased with age up 

through four years, then declined. However, monopodial 

plants showed neither of these age effects and no increase 

in stem diameter with age. The sympodial stems had 

significantly more cellulose than their monopodial 

counterparts, providing them with a higher stress yield. 

The predominance of these two forms differs with habitat, 

with more northern populations lacking the sympodial 

branching that defines the annual increments. Økland 

(2000) further determined that reproductive capacity differs 

with stem position and age. The apical tips are subject to 

greater exposure and are less likely to have successful 

reproduction. Reproductive failure is greatest for older 

segments buried within the weft (44%), lowest for 

intermediate vertical positions (12%), and relatively high 

for the emergent segments. The greatest annual increment 

is likewise at this intermediate level (2-10 mm below the 

bryophyte surface) where there is still sufficient light but 

the loss of water is minimized. 

Økland (2000) pointed out the importance of "growth 

form" in the way that pleurocarpous and acrocarpous 

bryophytes interact in competition. In our study on Isle 

Royale (Raeymaekers, Zhang, & Glime unpubl), the 

interaction between the acrocarpous Dicranum polysetum 

and the pleurocarpous Pleurozium schreberi (Figure 7) 

differed from year to year, most likely depending on the 

precipitation patterns. In some years, D. polysetum 

increased in area and overran P. schreberi, but in other 

years the reverse occurred. Økland suggested that the 

relationship of upper segments to lower ones represented 

amensalism, where the lower segments were harmed. 

Small segments were more easily buried. This relationship 

can play an important role in both infraspecific and 

interspecific 

interactions among bryophytes. 

Figure 7. Pleurozium schreberi competing with Dicranum 

polysetum. Photo by Herschel Horton.

Life Forms 

Literature on life forms and growth forms is confusing 

because different authors have used the terms in different 

ways, sometimes in reverse of the descriptions above. 

Even in the long-studied tracheophytes, the terms have 

often been used as if they are interchangeable. In studying 

loblolly pine trees, Haney et al. (1993) illustrated effects of 

density on "growth form" of loblolly pine tree shape. They 

found that in low densities, trees were shorter and had more 

branches. At medium density, they were taller, but 

branches were few in number. At high densities, trees were 

tallest and branches were still few (Figure 8). These 

environmental influences on tree form fit the more 

encompassing definition of life form described above by La 

Farge-England (1996). As expected, allocation of biomass 

changes relative to density (Table 1), resulting in a 

different form. Such mosses as Sphagnum and Climacium 

would be interesting tests of a similar form change in 

bryophytes. Climacium is known to change form, but it 

appears to be under both environmental and genetic 

control; 

effect of crowding was not studied (Shaw 1987). 

Figure 8. Illustration of forms in loblolly pine at different 

densities. Based on Haney et al. (1993). 

Table 1. Allocation of biomass in trees of loblolly pine at 

three density levels (Haney et al. 1993). 


low medium high 

diameter (cm) 11.87 7.79 6.67 

number of whorls 18 11 9 

biomass (kg) 12 6.5 4.9 

crown ratio 0.79 0.52 0.44 

branches 50 27 21 

branch length (m) 1.5 1.05 0.9 

Bates (1998) raised the question "Is 'life-form' a useful 

concept in bryophyte ecology?" When he pointed out that 

most bryophytes are either clonal or colonial, he 

emphasized that it is these, not individual shoots, that are 

the functional units. The life form maximizes productivity 

and minimizes water loss, but it may also function to 

prevent photoinhibition or scavenge cloud water. Despite 

its usefulness in indicating moisture and light conditions, 

Bates considers life form to have limited use "as a 

framework in ecological studies." He also considers a 

major problem to be the inconsistent way the concept has 

been applied in the literature. Life forms also change, as 

pointed out by Warming (1896). Bates suggested that one 

interpretation of life form is to consider highly productive 

horizontal growth forms like that of Brachythecium 

rutabulum (Figure 9) to be an adaptation for foraging 

(horizontal growth that permits mosses to take wider 

advantage of nutrients and light; Bates 1998). Life forms 

do not evolve independently and are closely tied to the life 

cycle and reproductive traits. Nevertheless, Bates 

concluded that the concept was useful because of "the high 

dependence of bryophytes on external transient water 

supplies." However, the description of life form alone will 

provide insufficient understanding and will depend on 

knowledge of its relationship to other attributes of the life 

strategy. 

Figure 9. Horizontal growth form of Brachythecium 

rutabulum that may be used for light scavenging (foraging). 

Photo by Michael Lüth. 

Age changes the life form and its effect on the 

physiology of Grimmia pulvinata (Figure 10) in a different 

way (Zotz et al. 2000). As discussed in the structural 

adaptations related to water, this moss forms cushions. As 

the cushion volume increases, so does the water volume. 

However, the surface area increases two-dimensionally as 

the volume increases three-dimensionally, causing a 

decrease in the surface area to volume ratio. This greatly 

enhances the water retention of the cushion as it enlarges. 

On the other hand, the CO2 exchange decreased with size, 

again because of the reduced surface area. Lowered CO2 

exchange corresponded with lower rates of both net 

photosynthesis 

and dark respiration. 

Figure 10. Cushion life form of Grimmia pulvinata. Photo 

by Des Callahan. 

Nevertheless, life forms are often indistinct from 

growth forms. A plant is predisposed to a certain growth 

form, and despite neighbors or environmental conditions, it 

retains that growth form as part of its life form. In this 

sense, Mägdefrau (1982) lists ten life forms for bryophytes 

(Figure 11, Figure 12), to which I (Glime 1968) have added 

streamer.


Figure 11. Life forms of mosses and liverworts, based on Mägdefrau (1969). Redrawn by Margaret Minahan.


Figure 12. Life forms of bryophytes. a. Annual – Ephemerum minutissimum. b. Short turf – Barbula unguiculata. c. Tall turf – 

Polytrichum formosum. d. Mat – Plagiothecium curvifolium. e. Pendant – Meteorium. f. Fan – Neckera urnigera. g. Dendroid – 

Pleuroziopsis ruthenica. h. Streamer – Fontinalis antipyretica. Photos by Michael Lüth; e & g by Janice Glime.


Mägdefrau Life Forms 

Annuals – pioneers; no vegetative shoots remain to carry on a 

second year; Buxbaumia (Figure 5), Diphyscium, Ephemerum 

(Figure 12a), Phascum, Riccia 

Short turfs – open mineral soils and rocks; regenerative shoots; 

form spreading turfs for only a few years; Barbula (Figure 

12b), Ceratodon, Didymodon, Marsupella 

Tall Turfs – forest floors in temperate zones; can conduct water 

internally; very tall; persist by regenerative shoots; 

Bartramiaceae, Dicranaceae, Polytrichaceae (Figure 12c), 

Drepanocladus, Herbertus, Sphagnum, Tomenthypnum 

Cushions – rocks, bark, Arctic, Antarctic, alpine; usually high 

light; grow upward and sideways; hemispherical; persistent for 

many years; Andreaea, Grimmia, Leucobryum (Figure 13), 

Orthotrichum, Plagiopus, no liverworts 

Mats – rocks, bark, [on leaves (epiphyllous) in tropics]; 

plagiotropic and persistent for a number of years; 

Lejeuneaceae, most Marchantiaceae, Homalothecium, 

Lophocolea, Plagiothecium (Figure 12d), Radula 

Wefts – forest floor of temperate zone; hold considerable 

capillary water; grow loosely and easy to remove from 

substrate; new layer grows each year; Brachytheciaceae, 

Hylocomiaceae (Figure 6), Bazzania, Ptilidium, Thuidium, 

Trichocolea 

Pendants – epiphytes, especially in tropical cloud forests; long 

main stem with short side branches; Meteoriaceae (Figure 

12e), Phyllogoniaceae, some tropical Frullania 

Tails – on trees and rocks, shade-loving; radially leafed, creeping, 

shoots stand away from substrate; Cyathophorum, Leucodon 

(Figure 4d), Spiridens, some tropical Plagiochila 

Fans – on vertical substrate, usually where there is lots of rain; 

creeping, with branches in one plane and leaves usually flat; 

Neckeraceae (Figure 12f), Pterobryaceae, Thamnobryum, 

some Plagiochila 

Dendroids – on ground, usually moist; main stem with tuft of 

branches at top; Climacium, Hypnodendron, Hypopterygium, 

Leucolepis, Pleuroziopsis (Figure 12g), Symphogyna 

hymenophyllum 

Streamer – long, floating stems in streams and lakes; Fontinalis 

(Figure 12h) 

Environmental Influences on Life Form 

These eleven forms may be further divided, as 

suggested by Horikawa and Ando (1952). As Mägdefrau 

(1982) points out, light and water are the predominant 

influences on life forms. Crowded shoots with dense 

foliage facilitate water movement and retention in areas 

with sufficient soil water, thus favoring tall turfs. Mats, 

wefts, tails, and fans, on the other hand, are unable to 

obtain water by capillary action, but depend on the 

capillary spaces to retain water and extend their periods of 

activity. Pendants (Figure 12e) are like laundry on the 

clothesline and are particularly susceptible to drying; hence 

they live in places with considerable rainfall or fog, 

assumedly directing the water to the growing tip. 

Mägdefrau (1982) cites his observations on mosses near 

waterfalls to support this assumption. 

The cushion life form (Figure 13) is highly adapted for 

water conservation. Proctor (1980) found that the laminar 

flow patterns over moss cushions were consistent with the 

measured loss of water from surfaces of varying degrees of 

roughness. Water loss increased rapidly beyond a critical 

wind speed, at which the surface irregularities of the 

cushion could be related to boundary-layer thickness. The 

thickness of this boundary layer determines the rate of 

water loss, with thick layers reducing evaporation. Even 

cushions have turbulent flow as opposed to laminar flow 

(Rice et al. 2001), and the more deeply the air penetrates 

into the moss canopy, the more turbulent that flow and the 

greater the evaporation. Among the growth forms, we 

would expect cushions to have the least turbulence, with 

wefts and turfs creating more (Figure 14). Surface 

roughness increases conductance (Rice et al. 2001). 

However, Proctor (1980) found that hair-points of the 

leaves that project above the cushion surface reduce 

boundary layer conductance, for example, by about 20-35% 

in Syntrichia intermedia and Grimmia pulvinata (Figure 

10), 

hence serving as an adaptation to reduce water loss. 

Figure 13. Cushions of Leucobryum glaucum in a mixed 

hardwood forest in the Keweenaw Peninsula of Michigan, USA. 

Photo by Janice Glime. 

Figure 14. Diagram indicating turbulence and boundary 

layer as might be found above the irregular surface of a moss 

weft. Having all stems at the same height, as in a cushion, would 

reduce the turbulence. Drawing by Margaret Minahan. 

Rice et al. (2001) have used wind tunnel experiments 

to examine effects of architectural features on boundary 

layer thickness and subsequent water balance of 

bryophytes. Using evaporation rates of ethanol, they were 

able to assess differences among 11 taxa having a variety 

of canopy structures. They accounted for 91% of mass 

transfer of water loss using models based on surface 

structure. Even the seemingly smooth surface of cushions 

behaved as turbulent flow rather than laminar flow

oundary layers. Conductance increased with surface 

roughness, causing those species with greater roughness to 

have higher conductance rates at all wind speeds. 

Water-holding capacity is often more important than 

obtaining water. In the Antarctic, dense rhizoids contribute 

to high water-holding capacity in Bryum algens (Lewis 

Smith 1988). In Schistidium antarcticum (Figure 15), the 

turf form has a high water-holding capacity, whereas the 

densely packed cushion form has a lower water content 

relative to its dry weight. Nevertheless, the rate of water 

loss is much more rapid in the turf form (Lewis Smith 

1988). I am puzzled, however, by the more rapid water 

loss in the more tomentose form of Bryum algens than in 

the form with fewer rhizoids. I would have to conclude 

that water was held loosely among the rhizoids, 

contributing to the magnitude of weight loss, and was lost 

more easily, giving a higher percentage loss. A similar 

phenomenon could explain the differences between the 

water loss of the turf and cushion. Lewis Smith found that 

the reverse relationship holds if the water loss is expressed 

relative to the initial water content instead of the dry 

weight, 

supporting my interpretation. 

Figure 15. Cushions of Schistidium antarcticum on 

Macquarie Island in the Antarctic. Photo by Rod Seppelt. 

Physical factors of the environment also contribute to 

life form in other ways. Once the growing apex reaches the 

surface of the cushion or exceeds the protection of a rock, 

it would be exposed to air movement where it would dry 

out. However, the ethylene concentration around the 

growing tip would also diminish. Whenever the moss 

slowed its growth and fell below its fellow cushion 

members, the higher ethylene concentration trapped within 

the cushion could again accelerate its cell elongation. 

Results with Fontinalis squamosa suggest that ethylene in 

mosses reduces cell division but permits and perhaps 

enhances cell elongation (Glime & Rohwer 1983). If it 

indeed acts this way, such a mechanism could be a 

sensitive and effective control mechanism that would 

maintain the cushion growth form necessary for maximum 

moisture retention (Kellomaki et al. 1978) and surface 

light. If, however, ethylene retards elongation as it does in 

most tracheophytes (Abeles 1973), IAA (indole acetic acid, 

a growth hormone) is probably the controlling factor. IAA 

is destroyed by light (Goodwin & Mercer 1983), so those 

branches getting more light would grow less, not to 

mention being retarded by desiccation, whereas those 

within the mat would be shaded and grow more, as an 

etiolation response. Mosses kept humid in a plastic bag in 

Chapter 4-5: Adaptive Strategies: Growth and Life Forms 

a place where little light reaches them produce narrow, 

etiolated shoots. In a terrarium, Dicranum scoparium, 

Pleurozium schreberi, and Brachythecium all produce 

etiolated tips, presumably in response to low light (pers. 

obs.). 

Plants, including bryophytes, have specific 

mechanisms to combat light intensity changes. Species 

from open habitats respond to simulated shade with a large 

increase in stem elongation (Morgan & Smith 1981). This 

increase would carry the plant upward until it topped its 

competitors and could receive the needed sunlight. 

Lignified woodland species react much less or not at all; 

here the futile attempt to top the canopy would result in 

tremendous amounts of wasted energy. Cushion 

bryophytes, however, respond to shading by each other like 

species from open habitats. In nature we see rounded 

cushions of Leucobryum and Dicranum, and we must 

wonder if the tall center plants and short border plants are 

merely a function of age. Yet when a clump is backed up 

against a rock, it is not as short on the rock side as it is on 

the other side, but rather it tapers down and away from the 

rock. Is it light intensity acting on IAA, exposure to 

desiccation, or ethylene concentration that maintains these 

cushions, or some combination of these? 

In mangrove swamps, Yamaguchi and coworkers 

(1990) found that small, appressed liverworts, especially 

Lejeuneaceae and Frullaniaceae, predominated, whereas in 

more landward sites the larger ascending taxa such as 

Plagiochila and pleurocarpous mosses were found. This 

distribution seems counter-intuitive unless the seaward 

sites were more subject to wind desiccation from buildup 

across the water, whereas the more landward ones were 

protected by the forest. Salt tolerance may enter the 

relationship as well, but this has not been explored. 

Birse (1957) showed that a normally monopodial 

dendroid Climacium dendroides can be induced to grow 

horizontally as a stolon when affixed to a substrate and 

supplied with ample moisture. It furthermore will reverse 

its direction of growth if turned upside down, yet, if placed 

in a moist pot, it will follow the substrate, growing down 

on the outside of the pot and ignoring gravity. If buried in 

sand, it will regenerate shoots that Birse et al. (1957) 

observed to grow up to the surface, then grow horizontally. 

She likewise observed that Thamnobryum alopecurum 

exhibited growth forms ranging from simple branches in 

dripping water to highly dendroid in very moist air. 

Aquatic mosses such as Fontinalis do not fall easily 

into the above classification system. While most Fontinalis 

species hang in a pendant form similar to pendant 

epiphytes, their physiological relationship to their 

environment as a result of this growth form is quite 

different. The tip, instead of receiving water dripping 

down from the remainder of the plant, is immersed most of 

the year. This long form, which I have termed streamer 

(Glime 1968; Jenkins & Proctor 1985) is more likely a 

result than an adaptation. The persistent growth of this 

moss permits it to grow farther and farther from its 

substrate, but many branches stack upon each other to 

make a thick weft, but one that is not easy to remove from 

the substrate. In Fontinalis dalecarlica, rhizoids are 

generally restricted to bases of stems, and the long, 

persistent stems are extremely strong (Glime 1980). In F. 

novae-angliae, rhizoids originate throughout the stems, 

45


making a firmer attachment to the substrate. It would be 

interesting to examine competition in these two taxa since 

they can occupy the same streams and even the same rocks. 

Although many studies describe dominant life forms, 

these descriptions are rarely based on quantitative data. 

Kürschner (1994) used mean cover values to describe life 

forms on basic rocks in nine communities in southern 

Germany on the northern border of the Schwaebische Alb. 

He found that communities subject to high light and 

temperature (photophytic and thermophytic) were 

dominated by cushions, short turfs, and perennial and 

short-lived colonists (life strategies discussed in the next 

chapter). As these graded into shady habitats, wefts and 

mats were more common, with perennial shuttle and 

perennial stayer life cycle strategies; reproduction was 

more "passive." Low light species (sciophytes) and aquatic 

species were perennial fan-formers with sexual 

reproduction. 

Physical Effects on Growth Form 

Moss Balls 

The strange phenomenon of moss balls was reported in 

1912 by Dixon, who referred to them as "mosses growing 

unattached." Bryologists still remain fascinated by these 

strange organisms that grow in a ball and are mobile, so 

that at different times any part of the sphere may be 

exposed to sunlight or substrate. But bryologists are not 

the only ones fascinated by them. In Japan, a monument is 

dedicated to their preservation (Iwatsuki 1977). 

In 1874, the United States sent an expedition to the 

Kerguelen Islands in the South Indian Ocean to observe the 

transit of Venus (Mägdefrau 1987). The surgeon of the 

expedition was also an amateur botanist and an avid 

collector. He brought back a "curious moss" that seemed 

"not to be rooted to another plant, but to be blown about by 

the wind indiscriminately," as described by the bryologist 

Th. P. James. Schimper later described these same mosses 

as having a size that varies between that of a cherry and a 

middle-sized potato. The smaller balls were Blindia 

aschistodontoides, and the larger ones were formed by 

stems of Andreaea parallela by radiating from a central 

core of soil or a small pebble. Since then similar windformed 

balls have been found in Alaska, Iceland, Norway, 

on Mount Ontaka in Japan, and even at the high elevation 

tropics of Mount Kenya, Mt. Elgon, and Mt. Kilimanjaro in 

Africa. 

Such balls in Arctic and alpine areas could result from 

solifluction. Solifluction is a slow creeping of fragmented 

material down a slope over impermeable material, due to 

the viscous flow of water-saturated soil and other surficial 

materials, particularly in regions underlain by frozen 

ground (not necessarily permafrost) acting as a barrier to 

downward water percolation. Its drift typically occurs at a 

rate of 1-10 cm per year (White 2001) in relatively cold 

regions when the brief warmth of summer thaws only the 

upper meter or two of loose earth materials above solid 

rock, which becomes waterlogged because the underlying 

ground remains frozen and therefore the water cannot drain 

down into it. Mosses could travel and tumble with it. 

Hedberg (1964) interpreted the African balls (Grimmia 

ovalis; Mägdefrau 1987) to form as a result of solifluction. 

Mägdefrau (1987) tested this hypothesis by experimenting 

with balls in Teleki Valley of Mount Kenya at 4200 m. 

The balls were marked and their locations sketched. When 

it was dry, there was no solifluction and the moss balls 

remained in place. However, when they experienced daily 

watering and frost at night, the balls rotated but held their 

positions. Rather, it appears that when ice crystals and ice 

needles form at night, they cause the mosses to be forced 

away from their substrate and broken off. These freed 

mosses are blown about continuously and thus grow in all 

directions, forming balls. 

Mägdefrau (1987) observed that none of the mosses in 

balls had sporophytes, whereas those of the same species 

growing attached had plentiful sporophytes. He concluded 

that the growth of sporophytes is prevented by the rolling 

movement. It would seem likely that young setae and 

perhaps even archegonia at apices may be damaged by 

abrasion as they get beaten around over the rocky surface. 

When mosses lie for a longer period of time on one side, 

sporophytes develop on the edge of the disk. 

On frozen Icelandic soil (Mägdefrau 1982) and 

Alaskan glaciers (Shacklette 1966; Heusser 1972; Iwatsuki 

1976), dislodged mosses blow about across the surface, 

forming similar balls. During (1992) observes that this life 

form, which also includes lichen species, results in areas 

that have high winds and little vegetation. 

Perez (1991) attributes the transport of Grimmia 

longirostris moss balls in the Paramo de Piedras Blancas of 

the Venezuelan Andes to needle ice activity. These balls 

had a high organic content (19%) and a collection of fine 

mineral grains (69%), a much higher fine grain than in the 

underlying mineral soils. This combination of organic 

content and fine grains affords the moss balls a much 

higher water retention capability than paramo soil, with 

water-holding capacity increasing with the size of the ball. 

Wind and ice are not the only sources of creating moss 

balls. Action of waves can create similar assemblages 

(Figure 17). These strange assemblages of individuals have 

been reported from as distant places as Alaska (Iwatsuki 

1976), Finland (Luther 1979), Japan (Iwatsuki 1956, 1977; 

Iwatsuki et al. 1983), and South America (Eyerdam 1967). 

Eyerdam found Fontinalis in balls up to 15 cm in diameter! 

In shallow water near lake shores in Hokkaido, Japan, 

Drepanocladus (Warnstorfia) fluitans (Figure 16) attaches 

to small rocks (Iwatsuki 1956); once the rock is dislodged, 

wave action rolls the moss back and forth, causing it to lie 

first in one position, then another, with any protruding 

branches being broken off (Iwatsuki et al. 1983). These 

growths become extremely dense. As the mosses reach 

shallower water, wave action is even greater. Ultimately 

they may be deposited in great numbers along the beaches. 

Stress causes the production of ethylene, and ethylene can 

result in short, wide cells under stress conditions in higher 

plants (Abeles 1973). This could partly explain the short, 

but 

firm, branches in the moss balls. 

Figure 16. Drepanocladus (Warnstorfia) fluitans growing 

normally. Photos by Michael Lüth.

Figure 17. Moss balls of Drepanocladus (Warnstorfia) 

fluitans var. kutcharokensis of Lake Kutcharo, Japan. Top: Moss 

balls being made by wave action. Second: Row of moss balls 

along shore. Third: Moss ball with arrows indicating green, 

growing apices. Bottom: Side branch typical of many of the 

stems in these balls, creating the dense structure that makes the 

ball. Photos by Janice Glime; bottom photo by Zen Iwatsuki. 

Even animals can create moss balls. In the Dutch 

wetland forest, it is foraging pheasants that turn the mosses 

upside down and initiate the upward growth that creates the 

ball (Wiegers 1983). Although Dicranum scoparium and 


Mnium hornum formed such balls, other upturned wetland 

taxa did not. 

Adaptive Significance 

Often the life form is a passive response to exposure; 

any protruding individual is more subject to desiccation 

and hence has a shorter period in which to be active for 

photosynthesis, thus reducing its growth rate below that of 

its shorter but hydrated neighbors. Although this is more 

commonly known in cushions, Perez (1991) found that the 

same phenomenon occurs in moss balls of Grimmia 

longirostris in the Venezuelan Andes. This spherical life 

form holds more water than the soil, and larger balls hold 

more than small ones. In some cases, the form may be 

modified to accommodate the capture of cloud water or to 

avoid photoinhibition. 

Mägdefrau (1935) found a clear relationship between 

life form and type of conduction. Dense tufts increase 

conduction, but there is considerable humidity difference 

within the tuft that suggests an important role in water 

retention (Zacherl 1956). When the air humidity is only 

50% a few cm above the tuft, it can be as much as 90% 

within the tuft. Larger volumes are able to store more 

water, and volume increases more rapidly than surface 

area. Larger cushions have a greater volume of water per 

unit of surface area, thus losing less to evaporation than 

small cushions with a thinner boundary layer and greater 

proportion of surface area (Proctor 2000). Zotz et al. 

(2000) used Grimmia pulvinata to demonstrate that the 

greater the size of the cushion, the more resistance it had to 

water loss. This size increase had no effect on the waterholding 

capacity on a dry mass basis, and the combination 

of these two factors contributed significantly to the length 

of the hydration period. 

The cushion growth form (Figure 18) is important in 

decreasing the loss of water by reducing the turbulence of 

airflow (Figure 14). At low and even moderate wind 

speeds, the evaporative water loss from the cushion mimics 

that of a flat or rounded surface of the same area (Proctor 

1984). This form is reminiscent of the tundra formations, 

where the cushions of seed plants not only impart 

resistance to moisture loss, but facilitate warming and 

protect from wind damage. The cushion shape presents a 

boundary layer that resists loss of moisture and permits 

wind to cross the plants with a minimum of disruption. 

Proctor (1979, 1980, 1982) found that the resistance to 

water loss extends the period of active metabolism after the 

precipitation stops. Nobuhara (1979) showed that Bryum 

argenteum increased its water-holding capacity as the 

volume increased, with more than 100 shoots reducing the 

water loss to something very small. 

The wind also can play a role in the formation of the 

cushion. As a branch, whether moss or tracheophyte, 

grows above the cushion, drying and wind action slow its 

growth and may even damage the terminal bud. Proctor 

(1980) demonstrated that when such surface irregularities 

reach the thickness of the boundary layer, there is a rapid 

increase in water loss at higher wind speeds. Thus, when a 

branch extends beyond the cushion, the other branches can 

catch up with it in growth before it is able to regain 

hydration and resume its growth, and if the terminal bud 

has 

been damaged, that growth may never occur. 

47


Figure 18. Leucobryum glaucum cushions. Photo by Janice 

Glime. 

Lewis Smith (1988) described the ability of dense turfs 

of Schistidium antarcticum (Figure 19) to hold strongly to 

their water content, but that the less densely packed shoots 

of cushions in xeric conditions could not maintain as high a 

water content as the turfs. Longton (1979a, b) drew a 

similar conclusion, noting that in Antarctica the plant size 

decreases as the shoot density increases; the shorter, more 

compact growth form could be adaptive to the cold, 

relatively dry habitats. 

Figure 19. Dense growth of Schistidium antarcticum on 

Macquarie Island in the Antarctic. Upper: dense and wellhydrated 

turf with Ceratodon purpureus growing in the crevices. 

Lower: Uneven turf with exposed tops exhibiting dehydration. 

Photo by Rod Seppelt. 

For endohydric mosses, growth form is important in 

water retention. Longton (1979a) found variations in the 

seasonal growth patterns of Hypnum cupressiforme, and 

was able to relate these to water supply. Gimingham and 

Birse (1957) related growth form response to decreasing 

levels of moisture: 

Relationship of Growth Form to Moisture 

high moisture 

dendroid & thalloid mats 

rough mats 

smooth mats 

short turfs & cushions 

low moisture 

Birse (1957) found that in some cases the growth form 

of certain species of bryophytes is almost invariable, 

whereas in others variation occurs according to the 

conditions of the habitat. Birse (1958a), reported that as 

long as there was a constant ground water supply, a variety 

of growth forms could flourish, especially tall turf and 

dendroid forms. In the absence of ground-water supply, 

short turfs, round mats, and one dendroid species 

(Climacium dendroides, Figure 20) were the only forms to 

survive. 

Dendroid mosses would seem to be particularly 

vulnerable to desiccation, with only a single stem in contact 

with the substrate and many exposed branches. Lorch 

(1931) found a correlation between the development of the 

central strand and the degree of branching, whereas the 

rhizome central strand became less developed, suggesting a 

greater importance for aerial water sources over soil 

sources as branching increased. Trachtenberg and Zamski 

(1979) supported these findings, re-affirming the 

importance of water absorption through the whole surface 

of the gametophyte and the utility of apoplastic transport. 

Figure 20. Climacium dendroides, showing dendroid growth 

form. Photo by Michael Lüth. 

Sollows and coworkers (2001) concluded that the 

colonial growth form of Bazzania trilobata (i.e. having 

branches lying on top of other branches; Figure 21) 

protected at least some inner shoots from the extreme 

exposures they experienced following clearcutting, 

avoiding the extinction of net photosynthesis observed in 

laboratory experiments following dehydration for 1-12 

days. 

Nakatsubo (1994) compared growth forms in the 

subalpine region in Japan and found that xeric species were 

indeed often large cushions, as well as compact mats. 

Mesophytic species, on the other hand, comprised smooth 

mats, wefts, and tall turfs on the coniferous forest floor. 

He demonstrated that the evaporative rate per dry mass was 

indeed much less in the xerophytic cushions and compact 

mats than in the mesophytic forms. While the evaporative

ate and dry mass were closely correlated with the growth 

form, the evaporative rate per basal area was not 

necessarily smaller in xerophytic taxa. 

Figure 21. Bazzania trilobata, illustrating the overlapping 

nature of the branches. Photo by Janice Glime. 

During (1979) likewise related the growth form to the 

habitat. He found that Campylopus flexuosus, 

Orthodicranum montanum, and several other taxa form 

large turfs with almost no vegetative reproduction when 

living in moist, undisturbed environments, but when found 

in dry forests they consist almost entirely of dense cushions 

of easily detached branchlets. 

But what empirical evidence do we have that the 

various growth forms and life forms actually afford any 

moisture advantage? Hanslin and coworkers (2001) 

demonstrated that increased shoot density of Dicranum 

majus and Rhytidiadelphus loreus actually had a negative 

effect on relative growth rate and green biomass, but that 

these were optimal at intermediate shoot densities in 

conditions of low relative humidity. It is likely that these 

species suffered a trade-off between light availability and 

moisture advantage at higher densities. In contrast, Bates 

(1988) found that Rhytidiadelphus triquetrus, likewise a 

boreal moss, had optimal growth when the colonies were 

most dense (1000 shoots dm-2 ). Apparently in this case the 

dense packing of the shoots gives the advantage of reduced 

water loss and outweighs the disadvantage of reduced 

irradiance. 

Habitat Relationships 

Certain growth forms seem to fare best in certain kinds 

of habitats (Proctor 1990). In the absence of direct 

physiological evidence, we can use the observed field 

relationships to form hypotheses concerning the best life 

form strategies. 

Deciduous Woodlands 

Proctor (1990) suggests that large size and rapid 

growth are important for woodland and grassland 

bryophytes to permit them to grow above the litter and 

surrounding vegetation. This life form permits them the 

competitive life strategy. Moist, shady habitats are more 

favorable for smooth mats and small cushions, but larger 

taxa occur as well, taking advantage of nutrients in 

throughfall and exposing more surface area for 

photosynthesis. In her study of British deciduous 

woodlands, Birse (1958b) found that wefts and mats 


predominated, responding primarily to light as a 

determinant of abundance. 

In humid, montane tropical forests, pendant and fan 

forms provide the most surface area for interception of the 

limited light without sacrificing moisture in this humid 

climate (Proctor 1990). Furthermore, they are able to trap 

water from mist and clouds. However, the great exposure 

makes them vulnerable to air pollution. 

Pine Woods 

Using Proctor's principles as a guideline, then what 

should we expect in a pine forest where leaf litter is a 

minimal problem? Seim et al. (1955) examined a Jack pine 

forest (Pinus banksiana) in Itasca Park, Minnesota, USA, 

and found wefts and mats as the predominant growth 

forms, with cushions and turfs comprising most of the 

remaining taxa. Gimingham and Robertson (1950) 

likewise found predominately wefts in Northern Britain. 

However, in another study, Moul and Buell (1955) found 

the turf type to be predominant (84%) in a sandy coastal 

pine woods of New Jersey, as did Hamilton (1953) in the 

hills of central New Jersey, USA. In alpine regions of 

Japan, Nakatsubo (1994) found that mesophytic species 

consisted of smooth mats, wefts, and tall turfs on the 

coniferous forest floor. 

Epiphytes 

Horikawa and Nakanishi (1954) developed a key to the 

"growth" (actually life) forms of Japanese epiphytic 

bryophytes. In it they included small cushion, large 

cushion, turf, fascicular & shrubby, dendroid, simple 

feather, branching feather, mat, carpet, hardly pressed 

mat, loosely pressed mat, epiphyllous, pendulous. They 

pointed out that species will vary with growing conditions, 

causing the same species to be assigned to more than one 

type. 

Peatlands 

Some terrestrial and peatland bryophytes may solve 

the CO2 problem by a cushion or other dense growth form 

(e.g. Sphagnum) that provides CO2 mostly from their own 

transpiration stream. In fact, Sphagnum seems to take 

advantage of CO2 rising from deep in the peat, bringing up 

carbon stored there 1000 or more years earlier. Perhaps 

there is some advantage to having your living parts sitting 

on top of your dead parts! 

Aquatic 

Aquatic mosses such as Drepanocladus vernicosus 

rely on a water medium when submersed but benefit from 

close contact when emergent (Frahm 1978). Aquatic 

bryophytes are most constrained by CO2. The mat form of 

Nardia compressa and Scapania undulata is beneficial in 

water below 0.1 m s -1 where its leaf-area index permits it to 

exploit the low boundary-layer resistance of high velocities 

without incurring a high drag. On the other hand, the 

streamer form of Fontinalis provides the most exposure 

(maximum surface area) in relatively quiet water of less 

than 0.01 m s -1 where boundary-layer resistance is high. 

Nevertheless, Fontinalis, with the same streamer life form, 

occurs in very rapid and turbulent water of mountain 

streams. Perhaps the turbulence itself permits enough CO2 

to mix with the water for the moss to take advantage of its 

greater surface area. 

49


In the Antarctic, aquatic mosses showed the greatest 

plasticity when submerged compared to being grown in the 

air (Priddle 1979). Calliergon sarmentosum grew longer 

stems (longer internodes) and larger leaves in the water, 

whereas Sanionia uncinatus varied little from its terrestrial 

form. 

Deserts 

It is significant that Frahm (1978) found only 9% of 

the bryophyte flora of the Sahara to be pleurocarpous. In 

the moist boreal forest, pleurocarpous is the dominant 

form. Pleurocarpous mosses expose much more surface 

area to the drying atmosphere; rather, in the dry desert, 

small cushions and wefts (loosely interwoven, ascending 

shoots capable of growing out of the sand are better 

adapted to the dry and shifting substrate. 

Polar Regions 

Longton (1979b, 1982) followed the life forms that 

Gimingham and Birse (1957) attributed to the polar regions 

in attempting to compare the Antarctic to other polar areas. 

He considered four Arctic bryophyte habitats: wetlands, 

mesic communities, polar deserts, and bryophytedominated 

habitats. He considered wetlands to be 

dominated by the tall turf life form, with lesser 

representation of short turfs such as Seligeria polaris on 

small stones. 

Mesic communities had a wider range of life forms 

than the wetlands, but the tall turf was still a dominant, 

with short turfs and mat-forming species also among the 

dominants. Although Longton (1979b) recognized five 

habitat types among the mesic communities, these forms 

were generally common among all five mesic communities. 

However, in Iceland, the weft community joined the tall 

turf in prominence, along with mats of leafy liverworts. 

Furthermore, the birch woods there had abundant weft 

mosses. 

Gimingham and Smith (1971) showed that the 

Polytrichum alpestre and Polytrichastrum alpinum turfs 

lost water more slowly than Chorisodontium aciphyllum 

and Sanionia uncinatus in the same habitats, attributing this 

to the waxy cuticle on the former two. That P. alpinum 

loses only about 10% of its water when centrifuged 

suggests that most of its water is held internally compared 

to the 20% lost from Chorisodontium aciphyllum. 

The dry polar desert fellfields have cushions of both 

mosses and flowering plants, but other open areas have 

compact forms such as mats, carpets, and short turfs 

(Longton 1979b). 

The bryophyte-dominated communities are those 

unsuitable for most tracheophytes (Longton 1979b). These 

include boulders, cliffs, musk ox dung, and hollows where 

snowmelt is late. The latter supports large cushions and 

tall turfs with small flowering plants rooted among them. 

The liverwort Anthelia juratzkana (Figure 22) is common 

here. Small cushions form on boulders, cliffs, and other 

rocky habitats. Rock crevices harbor small mats and turfs. 

Large cushions form on stony and marshy ground near 

permanent rivers and streams, with few bryophytes in the 

streams themselves. Where bryophytes do occupy streams, 

they are mostly streamers and mats. 

Figure 22. Leafy liverwort, Anthelia juratzkana, forming 

black mounds on the surface. Photo by Michael Lüth. 

The most unique of the polar habitats are those 

enriched with nitrogen by animal dung and support dense 

communities of dung mosses (Splachnaceae). Bird perches 

and lemming burrows support short turfs of acrocarpous 

mosses (Longton 1979b). Soil fractures between the 

polygons support short turfs of cosmopolitan taxa such as 

Bryum argenteum, Ceratodon purpureus, Funaria 

hygrometrica, and Marchantia polymorpha. 

Racomitrium lanuginosum forms extensive heaths 

resembling very large cushions in areas where it can gain 

water from the saturated atmosphere (Longton 1979b). In 

areas with frequent precipitiation as well as mist, Sanionia 

uncinata forms moderately thick mats. 

In the Antarctic, stones and gravel of nearly level 

ground support short turfs and cushions (Longton 1979b). 

In addition to these, calcareous substrata may have mats. 

Rock crevices have short turfs, small cushions, and mats. 

Alpine 

Alpine habitats seem to support mosses that resemble 

miniature tracheophyte growth forms. Cushions are 

common, but also carpets cover the dirt and provide 

protection from erosion. In studying the Ukrainian 

Carpathian Mountain alpine region, Ulychna (1970) 

included, in addition to these, bunches, dendroid, and 

interlacements, the latter two primarily in the transition into 

forest. 

Studies Needed 

While these growth and life form relationships to 

habitat seem to be well supported by field studies of 

species present, there has been little attempt to demonstrate 

that the proposed water relationships actually benefit the 

bryophytes. Transplant experiments need to be performed 

that compare the water loss of the various forms in a range 

of habitats, as well as their survival in this adult form 

without 

the need for surviving an establishment stage.

Summary 

Growth forms are those genetically controlled 

characteristics of plants that determine their shape. 

These are manifest as acrocarpous with terminal 

perichaetia (including protonema mosses and turf 

mosses), pleurocarpous (plagiotropic, including 

thread mosses, comb mosses, and creeping-shoot 

mosses) with lateral perichaetia, cladocarpous with 

perichaetia terminal on lateral branches. Life forms 

encompass overall organization of growth form, 

branching pattern, general assemblage of individuals, 

and modification of a population by the environment. 

The most widely used classification of life forms 

includes annuals, short turfs, tall turfs, cushions, 

mats, wefts, pendants, tails, fans, dendroids, and 

streamers. These can be subdivided, and a few others 

may exist in less well known habitats. 

Growth forms and life forms of plants can aid in 

water retention by reducing air resistance, increasing 

boundary layer thickness, providing capillary 

spaces, and protecting each other. Thalloid forms 

protect one side of the plant at the expense of the other, 

but cuticular substances reduce the loss on the exposed 

side. Open growth forms (e.g. dendroid, rough mat, 

pendant) are more subject to water loss than compact, 

tight ones (e.g. smooth mat, short turf, cushion). The 

cushion form is able to provide the least surface 

exposure per unit of biomass and apparently has the 

lowest water loss rate. Conduction forms seem to 

correlate with growth forms, with dense turfs increasing 

conduction as well as water retention. 

Cushions and moss balls are formed as exposed 

shoots are broken off by force of wind, abrasion, and 

desiccation. Moss balls generally have a pebble at the 

center and arise in areas of wave action, wind on ice, 

solifluction (possibly), or other physical factors that 

tumble the moss. 

Deciduous forests require large size and rapid 

growth such as wefts and mats to obtain enough light 

and avoid burial by litter. Humid forests support 

pendants and fans that can get moisture from fog and 

mist. Pine forests have wefts and mats, but also 

cushions, turfs, and smooth mats. Epiphytes include 

mostly appressed taxa such as smooth mats and small 

cushions, but a variety of other forms are possible in 

sufficient moisture. Peatlands take advantage of 

density to conserve moisture. Aquatic bryophytes are 

limited by availability of CO2 and reduce the boundary 

layer resistance with mats or increase surface area with 

streamers. Desert mosses conserve water with small 

cushions and wefts. Polar regions support a variety of 

forms, depending on the habitat, with cushions 

predominating in habitats where tracheophytes also 

form cushions; turfs are common. Alpine bryophytes 

also benefit from the cushion form. 

Acknowledgments 

This chapter has benefitted from the help of Beth 

Scafone and Medora Burke-Scoll, who helped me explain 

things for beginning bryologists while at the same time not 

repeating myself. Linda Luster checked the literature 


citations, proofread, and made glossary suggestions from a 

layperson's perspective. 

Literature Cited 

Abeles, F. B. 1973. Ethylene in Plant Biology. Academic Press, 

New York. 

Barkman, J. J. 1979. The investigation of vegetation texture and 

structure. In: Werger, M. J. A. (ed.). The Study of 

Vegetation. The Hague, Boston, London, pp. 123-160. 

Bates, J. W. 1988. The effect of shoot spacing on the growth and 

branch development of the moss Rhytidiadelphus triquetris. 

New Phytol. 109: 499-504. 

Bates, J. W. 1998. Is 'life-form' a useful concept in bryophyte 

ecology? Oikos 82: 223-237. 

Birse, E. M. 1957. Ecological studies on growth-form in 

bryophytes. II. Experimental studies on growth-form in 

mosses. J. Ecol. 45: 721-733. 

Birse, E. M. 1958a. Ecological studies on growth-form in 

bryophytes. III. The relationship between growth-form of 

mosses and ground water supply. J. Ecol. 46: 9-27. 

Birse, E. M. 1958b. Ecological studies on growth-form in 

bryophytes. IV. Growth-form distribution in a deciduous 

wood. J. Ecol. 46: 29-42. 

Birse, E. M., Landsberg, S. Y., and Gimingham, C. H. 1957. The 

effects of burial by sand on dune mosses. Trans. Brit. Bryol. 

Soc. 3: 285-301. 

Dansereau, P. 1957. Biogeography – An Ecological Perspective. 

Ronald Press Co., New York, pp. 67-71. 

Dixon, H. N. 1912. Note on mosses growing unattached. 

Bryologist 15: 31-32. 

During, H. J. 1979. Life strategies of bryophytes: A preliminary 

review. Lindbergia 5: 2-18. 

During, H. J. 1992. Ecological classifications of bryophytes and 

lichens. In: Bates, J. W. and Farmer, A. M. (eds.). 

Bryophytes and Lichens in a Changing Environment. 

Clarendon Press, Oxford, pp. 1-31. 

Eyerdam, W. J. 1967. Letter to Bryologist. Bryologist 70: 394. 

Frahm, J.-P. 1978. Zur Moosflora der Sahara. Nova Hedw. 30: 

527-548. 

Frey, W. and Hensen, I. 1995. Lebensstrategien bei Pflanzen: 

ein Klassifizierungsvorschlag. [Plant life strategies: a 

preliminary system.]. Bot. Jahrb. Syst. 117: 187-209. 

Gimingham, C. H. and Birse, E. M. 1957. Ecological studies on 

growth-form in bryophytes. I. Correlations between growthform 

and habitat. J. Ecol. 45: 533-545. 

Gimingham, C. H. and Robertson, E. T. 1950. Preliminary 

observations on the structure of bryophyte communities. 

Trans. Brit. Bryol. Soc. 1: 330-334. 

Gimingham, C. H., and Smith, R. I. L. 1971. Growth form and 

water relations of mosses in the maritime Antarctic. Brit. 

Antarc. Surv. Bull. 25: 1-21. 

Glime, J. M. 1968. Ecological observations on some bryophytes 

in Appalachian Mountain streams. Castanea 33: 300-325. 

Glime, J. M. 1980. Effects of temperature and flow on rhizoid 

production in Fontinalis. Bryologist 83: 477-485. 

Glime, J. M. and Rohwer, F. 1983. The comparative effects of 

ethylene and 1-amino-cyclopropane-1-carboxylic acid on 

two species of Fontinalis. J. Bryol. 12: 611-616. 

Goodwin, T. W. and Mercer, E. I. 1983. Introduction to Plant 

Biochemistry, 2nd. ed. Pergamon Press, Oxford, 677 pp. 

Gould, S. J. and Lewonton, R. C. 1979. The spandrels of San 

Marco and the panglossian paradigm: A critique of the 

51


adaptationist programme. Proc. Royal Soc. Lond., Ser. B 

205: 581-598. 

Hamilton, E. S. 1953. Bryophyte life forms on slopes of 

contrasting exposures in central New Jersey. Bull. Torrey 

Bot. Club 80: 264-272. 

Haney, E. M., Christensen, N. L., and Kasischke, E. S. 1993. 

Density-related variability in loblolly pine (Pinus taeda L.) 

morphology and patterns of biomass allocation. Program 

and Abstracts, 78th Ann. ESA Meeting, 31 July - 4 August 

1993. Bull. Ecol. Soc. Amer. Suppl. vol 74(2): 264. 

Hanslin, H. M., Bakken, S., and Pedersen, B. 2001. The impact 

of watering regime and ambient relative humidity on the 

effect of density on growth in two boreal forest mosses, 

Dicranum majus and Rhytidiadelphus loreus. J. Bryol. 23: 

43-54. 

Hedberg, O. 1964. Features of Afroalpine plant ecology. ACTA 

Phytogeogr. Suecica 49: 1-144. 

Hennig, W. 1966. Phylogenetic Systematics. University of 

Illinois Press, Urbana. [Translated by Davis, D.D. and 

Zangerl, R. from Hennig, W. 1950. Grundzüge einer 

Theorie der Phylogenetischen Systematik. Deutscher 

Zentralverlag, Berlin.]. 

Heusser, C. J. 1972. Polsters of the moss Drepanocladus 

berggrenii on Gilkey Glacier, Alaska. Bull. Torrey Bot. 

Club 99: 34-36. 

Horikawa, Y., and Ando, H. 1952. A short study of the growthform 

of bryophytes and its ecological significance. Hikobia 

1: 119-128. 

Horikawa, Y., and Nakanishi, S. 1954. On the growth-form types 

of epiphytic bryophytes. Bull. Soc. Plant Ecol. 3(4): 203- 

210. 

Iwatsuki, Z. 1956. Letter on moss balls. Misc. Bryol. Lichenol. 

1(3): 1-2. 

Iwatsuki, Z. 1976. Moss balls from Arctic Alaska. Proc. Bryol. 

Soc. Japan 1: 183. 

Iwatsuki, Z. 1977. Nippon no tennenkinenbutsu no koke – 

hikarigoke to marigoke. [Schistostega pennata and moss 

balls – mosses designated as natural monuments in Japan.]. 

Shizenkagaku Hakubutsukan 44(2): 64-67. 

Iwatsuki, Z., Takita, K., and Glime, J. M. 1983. Moss balls of 

Lake Kutcharo, Hokkaido. Misc. Bryol. Lichenol. 9(9): 199- 

201. 

Jenkins, J. T. and Proctor, M. C. F. 1985. Water velocity, 

growth-form and diffusion resistances to photosynthetic CO2 

uptake in aquatic bryophytes. Plant Cell Environ. 8: 317- 

323. 

Kellomaki, S., Hari, P. and Koponen, T. 1978. Ecology of 

photosynthesis in Dicranum and its taxonomic significance. 

In: Suire, C. (ed.). Congres International der Bryologie, 

Bordeaux 21-23 Novembre 1977. Bryophytorum 

Bibliotheca 13: 485-507. 

Kürschner, H. 1994. Adaptionen und Lebensstrategien in 

basiphytischen Gesteinsmoosgesellschaften am Nordrand der 

Schwaebischen Alb (Sueddeutschland). [Adaptations and 

life-strategies of basiphytic bryophyte rock communities 

from the northern border of the Schwaebische Alb (southern 

Germany).]. Phytocoenologia 24: 531-558. 

La Farge-England, C. 1996. Growth form, branching pattern, and 

perichaetial position in mosses: Cladocarpy and pleurocarpy 

redefined. Bryologist 99: 170-186. 

Lewis Smith, R. I. 1988. Aspects of cryptogam water relations at 

a continental Antarctic site. Polarforschung 58: 139-153. 

Longton, R. E. 1979a. Climatic adaptation of bryophytes in 

relation to systematics. In: Bryophyte Systematics, 

Systematics Association Special Vol. No. 14, Academic 

Press, New York, pp. 511-531. 

Longton, R. E. 1979b. Vegetation ecology and classification in 

the Antarctic zone. Can. J. Bot. 57: 2264-2278. 

Longton, R. E. 1982. Bryophyte vegetation in polar regions. In 

Smith, A. J. E. (ed.). Bryophyte Ecology, Chapman and 

Hall, New York, pp. 123-165. 

Lorch, W. 1931. Anatomie der Laubmoose. In: Linsbauer, K. 

(ed.). Handbuch der Pflanzenanatomie VII/I. Gebrüder 

Bornträger, Berlin, 358 pp. 

Luther, H. 1979. Aquatic moss balls in southern Finland. Ann. 

Bot. Fennici 16: 163-172. 

Mägdefrau, K. 1935. Untersuchungen über die 

Wasserversorgung des Gametophyten und Sporophyten der 

Laubmoose. Zeitschr. Bot. 29: 337-375. 

Mägdefrau, K. 1969. Die Lebensformen der Laubmoose. 

Vegetatio 16: 285-297. 

Mägdefrau, K. 1982. Life-forms of bryophytes. In: Smith, A. J. 

E. Bryophyte Ecology. Chapman and Hall, London, pp. 45- 

58. 

Mägdefrau, K. 1987. Globular mosses. Bryological Times 41: 1, 

3. 

Meusel, H. 1935. Wuchsformen und Wuchstypen der 

Europaischen Laubmoose. Bot. J. Linn. Soc. 67: 46. 

Deutsche Acad. der Nat. Nova ACTA Leopolding N. F. 

3(12): 124-277. 

Mishler, B. D. 1988. Reproductive ecology of bryophytes. In: 

Lovett Doust, J. and Lovett Doust, L. (eds.). Plant 

Reproductive Ecology. Patterns and Strategies. Oxford 

University Press, New York & Oxford, pp. 285-306. 

Morgan, D. C. and Smith, H. 1981. Non-photosynthetic 

responses to light quality. In: Lange, O. L., Nobel, P. S., 

Osmond, C. B., and Ziegler, H. (eds.). Physiological Plant 

Ecology. I. Springer-Verlag, New York, pp. 109-134. 

Moul, E. T. and Buell, M. F. 1955. Moss cover and rainfall 

interception in frequently burned sites in the New Jersey pine 

barrens. Bull. Torrey Bot. Club 82: 155-162. 

Nakatsubo, T. 1994. The effect of growth form on the 

evaporation in some subalpine mosses. Ecol. Res. 9(3): 245- 

250. 

Nobuhara, H. 1979. Relationship between the number of shoots 

in a cushion and transpiration in Bryum argenteum. Proc. 

Bryol. Soc. Japan 2(7): 91-92. 

Økland, R. H. 2000. Population biology of the clonal moss 

Hylocomium splendens in Norwegian boreal spruce forests. 

5. Vertical dynamics of individual shoot segments. Oikos 

88: 449-469. 

Økland, R. H. and Økland, T. 1996. Population biology of the 

clonal moss Hylocomium splendens in Norwegian boreal 

spruce forests. II. Effects of density. J. Ecol. 4: 63-69. 

Perez, F. L. 1991. Ecology and morphology of globular mosses 

of Grimmia longirostris in the Paramo de Piedras Blancas, 

Venezuelan Andes. Arct. Alp. Res. 23: 133-148. 

Priddle, J. 1979. Morphology and adaptation of aquatic mosses 

in an Antarctic lake. J. Bryol. 10: 517-531. 

Proctor, M. C. F. 1979. Structure and eco-physiological 

adaptations in bryophytes. In: Clarke, G. C. S. and Duckett, 

J. G. (eds.). Bryophyte Systematics. Systematic Association 

special volume 14. Academic Press, London, pp. 479-509. 

Proctor, M. C. F. 1980. Diffusion resistances in bryophytes. In: 

Grace, J., Ford, E. D., and Jarvis, P. G. (eds.). Plants and 

their Atmospheric Environments, 21st Symp. Brit. Ecol. 

Soc., Edinburgh, pp. 219-229.

Proctor, M. C. F. 1982. Physiological ecology: Water relations, 

light and temperature responses, carbon balance. In: Smith, 

A. J. E. (ed.). Bryophyte Ecology. Chapman and Hall, 

London, pp. 333-381. 

Proctor, M. C. F. 1984. Structure and ecological adaptation. In: 

Dyer, A. F. and Duckett, J. G. (eds.). The Experimental 

Biology of Bryophytes. Academic Press, London, pp. 9-37. 

Proctor, M. C. F. 1990. The physiological basis of bryophyte 

production. International Symposium on Bryophyte Ecology 

Edinburgh (UK), 19-22 July 1988. J. Linn. Soc. Bot. 104: 

61-77. 

Proctor, M. C. F. 2000. Mosses and alternative adaptation to life 

on land. New Phytol. 148: 1-3. 

Raunkiaer, C. 1934. The Life Forms of Plants and Statistical 

Plant Geography. Clarendon Press, Oxford. 

Rice, S. K., Collins, D., and Anderson, A. M. 2001. Functional 

significance of variation in bryophyte canopy structure. 

Amer. J. Bot. 88: 1568-1576. 

Ricklefs, R. E. 1990. Ecology, 3rd ed. W. H. Freeman and Co., 

New York, 896 pp. 

Ross, S. E., Callaghan, T. V., Ennos, A. R., and Sheffield, E. 

1998. Mechanics and growth form of the moss Hylocomium 

splendens. Ann. Bot. 82: 787-793. 

Ross, S. E., Callaghan, T. V., Sonesson, M., and Sheffield, E. 

2001. Variation and control of growth-form in the moss 

Hylocomium splendens. J. Bryol. 23: 283-292. 

Seim, A. L., Buell, M. F., and Evans, R. I. 1955. Bryophyte 

growth forms and cover in a Jack pine stand, Itasca Park, 

Minnesota. Bryologist 58: 326-329. 

Shacklette, H. T. 1966. Unattached moss polsters on Amchitka 

Island, Alaska. Bryologist 69: 346-352. 

Shaw, J. 1987. Growth form variation within and between 

populations of Climacium americanum Brid. Symposia 

Biologica Hungarica 35: 555-567. 


Sollows, M. C., Frego, K. A., and Norfolk, C. 2001. Recovery of 

Bazzania trilobata following desiccation. Bryologist 104: 

421-429. 

Tangney, R. S. 1998. The architecture of the Lembophyllaceae 

(Musci). J. Hattori Bot. Lab. 84: 37-47. 

Trachtenberg, S. and Zamski, E. 1979. The apoplastic 

conduction of water in Polytrichum juniperinum Willd. 

gametophytes. New Phytol. 83: 49-52. 

Ulychna, K. O. 1970. Growth forms of Bryophyta of the 

Carpathian High Mountains. Ukranisk Bot. Z. 27: 189-196. 

Vilde, R. 1991. Role of life form in the formation of the water 

regime of mosses. Proc. Est. Acad. Sci., Ecol. 1(4): 173-178. 

Warming, E. 1896. Lehrbuch der ökologischen 

Pflanzengeographie. Bornträger, Berlin. 

White, I. 2001. Glacial and periglacial environments. The tundra 

environment. University of Portsmouth. Last modified 

December 2001. Accessed on 18 May 2006 at 

http://www.envf.port.ac.uk/geog/teaching/environ/ec2- 

3i.htm. 

Wiegers, J. 1983. Observations on the origin of "moss balls" in a 

Dutch wetland forest. Beitr. Biol. Pflanzen 58: 449-454. 

Yamaguchi, T., Nakagoshi, N., Nehira, K., and Iwatsuki, Z. 

1990. Epiphytic bryophyte flora in mangrove forests in 

Japan. Hikobia 10: 403-407. 

Zacherl, H. 1956. Physiologische und Okologische 

Untersuchungen über die innere Wasserleitung bei 

Laubmoosen. Z. Bot. 44: 409-436. 

Zotz, G., Schweikert, A., Jetz, W., and Westerman, H. 2000. 

Water relations and carbon gain are closely related to 

cushion size in the moss Grimmia pulvinata. New Phytol. 

148: 59-67. 

53

54 Chapter 4-5: Adaptive Strategies: Growth and Life Forms

Chapter 4-5: Adaptive Strategies - Bryophyte Ecology

Create successful ePaper yourself

Delete template?

Save as template?