Vallisneria

Scientific name

Vallisneria L.

Common names

tape grass, eel grass, American wild celery

Family

Hydrocharitaceae

Similar genera

Acorus, Blyxa, Crinum, Cyperus, Echinodorus, Egeria, Eriocaulon, Jasarum, Lagarosiphon, Nechamandra, Sagittaria, Stratiotes, Triglochin

Native distribution

tropical and some temperatetemperate:
(adj) of the climatic zone between boreal and tropical
regions of the world

Species cultivated

Vallisneria americana (Michx.) (and varieties)

V. annua S.W.L.Jacobs & K.A.Frank

V. asiatica Miki [synonym of V. natans (Lour.) H.Hara]

V. caulescens F.M.Bailey & F.Muell.

V. erecta S.W.L.Jacobs

V. nana R. Br. [also offered under the synonym V. gigantea Graebn.]

V. rubra (Rendle) Les & S.W.L.Jacobs [Maidenia rubra Rendle]

V. spiralis L. (and varieties)

V. triptera S.W.L.Jacobs & K.A.Frank

Adventive distribution

Unclear since the distributions of V. americana and V. spiralis are very broad and species identification is difficult.

Weed status

Vallisneria spiralis is considered a serious weed in more than 50 countries on all continents. This species is troublesome as it impedes water flow in irrigation canals and storage dams, blocking navigation, recreation, and agriculture.

Habit

submersed, attached rosetterosette:
(n) a radiating cluster of leaves, usually close to the ground at the base of a plant
or ascending stem plant

Brief description

Annual or perennialperennial:
(adj) (of a plant) having a life cycle of more than two years
, dioeciousdioecious:
(adj) having separate male and female flowers on different individuals of the same species
(V. rubra often monoeciousmonoecious:
(adj) having separate male and female flowers on the same individual
). Stem stoloniferous, compact or elongate. Leaves typically in a basalbasal:
(adj) at or pertaining to the base, or point of attachment
rosette, less often alternatealternate:
(adj) (of leaves) bearing one leaf per node; placed singly on the stem at different heights
or spiraling along elongate stem, sessilesessile:
(adj) attached directly, without a stalk
; leaf bladeblade:
(n) (syn. lamina) the flat, expanded part of a leaf, frond, or petal (excluding, e.g., the petiole)
strap-like, linear, highly elongate to less so, width variable, sometimes filiformfiliform:
(adj) thread-like; long and thin
, sometimes twisted, venationvenation:
(n) the arrangement of veins in a leaf
distinctly parallel; marginmargin:
(n) edge; rim
serrulate or with minute spines. Inflorescenceinflorescence:
(n) the arrangement of flowers on the floral axis
axillaryaxillary:
(adj) in, of, or produced from an axil
, may be in clusters (whorls) along stem; spathespathe:
(n) a large bract or bracts subtending and often enclosing an inflorescence
of two united bracts subtends flower(s); male flowers small, numerous; when spathespathe:
(n) a large bract or bracts subtending and often enclosing an inflorescence
opens flower buds liberated and open at water surface; female flower solitary, on a pedicelpedicel:
(n) the stalk of a single flower in an inflorescence, or of a grass spikelet
that elongates until flower reaches water surface and opens. Sepals 2-3, large (female flowers); 3, unequal, reflexedreflexed:
(adj) abruptly curved or bent downward
(male flowers); petals rudimentary or absent. Dispersal by seed and runners.

Natural habitat

still or running waters of rivers, streams, lakes, billabongs (ox-bow lakes), swamps, floodplains and artificial water bodies

Additional comments

The taxonomy of Vallisneria is highly problematic, resulting in numerous species being described and these names being widely distributed in the aquarium plant trade. Reliable identification of species is only possible by examining floral structures. Recent taxonomic consensus is that outside of Australia, there are two poorly defined species, V. americana and V. spiralis. Both species are now considered to contain numerous regional varieties: from the highly twisted narrow leaves of V. americana var. biwaensis (Miki) Lowden, to the very long and wide leaves (3 cm wide by >2 m long) of V. americana var. gigantea (Graebn.). Vallisneria caulescens F.M. Bailey & F. Muell. and V. triptera S.W.L. Jacobs & K.A. Frank are two closely related species from northern Australia that grow as stem plants, with leaves arranged alternately along the stems, rather than as compact, basalbasal:
(adj) at or pertaining to the base, or point of attachment
rosettes. Both species have recently been introduced to the aquarium trade. The closely related species Maidenia rubra Rendle was recently placed in Vallisneria based on morphological and molecular data.