Plagiomnium rhynchophorum (Hook.) T.J. Kop. subsp. rhynchophorum
Family: Mniaceae
Synonyms
Plagiomnium rhynchophorum var. carolinianum (L.E. Anderson) T.J. Kop.
Plagiomnium carolinianum (L.E. Anderson) T.J. Kop.
Mnium carolinianum L. E. Anderson
Other synonyms listed in Yi et al. (2018)
NatureServe Conservation Status
not assigned; G3 for Plagiomnium carolinianum
Distribution
North America. U.S.A. (Georgia, Kentucky, North Carolina, South Carolina, Tennessee), Mexico. Central America, South America, Asia, Africa, (Yi et al. 2018). Plagiomnium rhynchophorum subsp. maximoviczii occurs in Asia.
Habitat
Regionally, hemlock-hardwood stream ravines, usually in deep shade; on wet rock, humus, or soil along streams, cliff ledges, spillways and waterfalls. Zartman and Pittillo (1998) recorded the species as a member of the spray cliff community. Often found along small streams and seeps that feed into larger streams. A single specimen in Kentucky, Risk and Richardson 13946 (MDKY), is from limestone downstream from the mouth of a cave. Low elevations, 700-2700 ft.
Associated bryophytes include (most of the following from Anderson 1954) , MOSSES: Anomodon attenuatus, Arrhenopterum heterostichum, Ambylstegium tenax, Bryoandersonia illecebra, Bryocrumia vivicolor, Campylium chrysophyllum, Cirriphyllum piliferum, Ctenidium molluscum, Entodon sullivantii, Fissidens taxifolius, F. dubius, Hookeria acutifolia, Isopterygiopsis muelleriana, Leucobryum glaucum, Mnium hornum, Plagiomnium ciliare, Rhizomnium punctatum, Rhynchostegium aquaticum, Thamnobryum alleghaniense, and Thuidium delicatulum; LIVERWORTS: Chiloscyphus pallescens, Dumortiera hirsuta, Jubula pennsylvanica, Metzgeria leptoneura, Pallavicinia lyellii, Plagiochila porelloides, Porella pinnata, Radula sullivantii, Riccardia multifida, and Scapania nemorea.
Brief Description and Tips for Identification
Plants robust, dark green, fertile stems erect, forming tufts 2-3 cm high; sterile stems horizontal, 4-8 (20) cm long. Leaves spreading and undulate when moist, crisped and contracted when dry, 5-10 mm long, oblong-lingulate, apices retuse or emarginate, short-mucronate. Leaf margin with mostly one-celled, blunt teeth. Leaf base long-decurrent.
Synoicous. 1-4 sporophytes per fertile shoot tip. Outer cells of capsule wall bulging when moist, imparting a pebbly texture, when dry collapsing and imparting a roughened texture. Description derived from Crum and Anderson (1981) and McIntosh and Newmaster (2014).
In the Southern Appalachians, Plagiomnium rhynchophorum is most similar to P. rostratum (=Mnium longirostrum). Some forms of P. rostratum are so similar to Plagiomnium rhynchophorum that a specimen from Blowing Springs, Swain Co., NC, identified by Lewis Anderson as the synonym Plagiomnium carolinianum, was annotated to P. rostratum by Yan-Jun Yi (Anderson 10151, DUKE). The difficulty comes when some larger leaves of P. rostratum are nearly strap-shaped with weak undulations and slightly emarginate apices; however, many leaves in such specimens will be broadly elliptic without undulations. Similarities between the two species include a long-beaked operculum and leaf margins toothed to near the base with short blunt teeth. Differences include the outer cells of the capsule wall in P. rostratum lacking the distinctive collapsed shape when dry and swollen shape when hydrated, P. rostratum lacking the well-marked decurrencies of leaf bases, and P. rostratum lacking the decidedly strap-shaped leaves with strong undulations. Sporophytes in both species are often not present, thus identifications must often rely on vegetative characters.
Salient Features
- Leaves oblong-lingulate and undulate
- Leaf apex typically emarginate with a short mucro
- Leaves long-decurrent
- Cells of the outer capsule wall bulging when moist, collapsing when dried
References
Anderson, L. E. 1954. A new species of Mnium from the southern Appalachians. The Bryologist, 57(3), 177-188.
Anderson, L.E. 1996 (revised 1977 by Amoroso). Bryophyte Status Survey: Plagiomnium carolinianum (Anderson) T.Kop. North Carolina Heritage Program.
Crum, H. A., and L. E. Anderson. 1981. Mosses of Eastern North America (Vol. 1). Columbia University Press
Koponen, T.J. 2014. Bryophyte flora of Hunan Province, China. 18. Mniaceae subfam. Mnioideae (Musci). Acta Bryolichenologica Asiatica 5: 39–72
McIntosh, T. T., and Newmaster, S. G. 2014. Plagiomnium. In: Flora of North America, North of Mexico 28: 229–235.
Yi, Y. J., Sun, Z. W., He, S., and Sulayman, M. 2018. A study of molecular sequences, sexuality, and morphological variation in Plagiomnium carolinianum, P. maximoviczii, and P. rhynchophorum (Bryophyta, Mniaceae). Phytotaxa, 375(1), 81-91.
Zartman, C. E., and Pittillo, J. D. 1998. Spray cliff communities of the Chattooga Basin. Castanea, 217-240.
Acknowledgment
Some text and images on this page were originally prepared for the Georgia Department of Natural Resources in 2010, contract number 605-090427 with Paul G. Davison and used here with permission.
Habitat
Plagiomnium rhynchophorum
On wet soil along a very steep and long cascading streamlet in north Georgia. Most occurrences are on wet rock.
Plagiomnium rhynchophorum
This wet rock meeting the forest floor is part of a larger wet outcrop embedded in a steep slope about 5 meters in elevation above the floodplain of a nearby stream in north Georgia. The photo fails to capture any distinctive morphology of mosses. P. rhynchophorum is present with other mosses admixed.
Habit
Plagiomnium rhynchophorum
The long strap-shaped and undulate leaves make this a distinctive moss "recognizable in the field even without a handlens" (Anderson 1996).
Plagiomnium rhynchophorum
The large shoot near the center of the photo bears microscopic sex organs at the shoot tip. Archegonia and antheridia, invisible at this scale, are located in the brown stem tip surrounded by leaves. The admixed mosses Bryoandersonia illecebra and Plagiomnium clilare are labeled.
Plagiomnium rhynchophorum
Plagiomnium ciliare is a more coarsley toothed species lacking the emarginate leaf tips and distinctive undulations of the leaf blade that characterize P. rhynchophorum. Can you locate the unlabeled P. ciliare with large, coarsely toothed leaves lying in the wet muck near the center of the photo?
Morphology
Plagiomnium rhynchophorum
Open the image to 100 percent to see the cells of the outer capsule wall, collapsed-dry, swollen-moist.
Plagiomnium rhynchophorum
Image of long-dried herbarium specimen showing leaves "crisped and contorted when dry"--a character common to many species of Plagiomnium. In nature, P. rhynchophorum appears limited to habitats that rarely, if ever, dry out.
Plagiomnium rhynchophorum vs. P. rostratum
P. rhynchophorum vs. P. rostratum
A very robust specimen of P. rostratum (from limestone near a cave entrance) is compared to a less than robust representative of P. rhynchophorum. The leaf apices are rather similar between the two, but the specimens clearly differ in leaf shape. The undulations in the leaves of P. rhynchophorum are quite evident even though pressed flat by a coverslip.
P. rhynchophorum vs. P. rostratum
P. rhynchophorum possesses long-decurrent leaf bases that are easily demonstrated. Leaf bases of P. rostratum either lack decurrencies or are short-decurrent. The upper image of P. rostratum above illustrates the longest decurrency found in a robust specimen in which most leaves were hardly, if at all, decurrent.
P. rostratum
Leaves bear some similarity to those of P. rhynchophorum but are more elliptic than strap-shaped, lack the distinct undulations, and leaf tips are not as regularly emarginate.