Flora of North America species comparison

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Marsilea vestita

Marsileaceae

hairy clover-fern, hairy water-clover, pepperwort, water-clover, water-clover pepperwort, western water-clover

marsilea family, water-clover family
Habit Plants forming diffuse or dense clones. Plants aquatic or amphibious, rhizomatous.
Roots

arising at nodes.

arising at nodes and also along internodes.
Stems

growing on soil surface or subterranean, main stem long-creeping and giving rise to long or short shoots only at nodes;

hairs laterally attached, multicellular.
Leaves

distichous, long-petioled, sometimes filiform and lacking expanded blades.
Petioles

2–20 cm, sparsely pubescent.

Pinnae

4–19 × 4–16 mm, pubescent to glabrous.

Sori

14–22.

within hard bean- or pea-shaped bodies (sporocarps) arising on short stalks from near or at base of petioles.
Sporangia

of 2 kinds, borne within the same sorus and sporocarp;

megasporangia containing a single megaspore;

microsporangia containing 20–64 microspores.
Gametophytes

remaining within spores;

microgametophytes of only a few cells;

megagametophytes protruding from spores, each bearing 1 simple archegonium.
Sporocarp(s)

stalks erect, unbranched, attached at base of petiole (occasionally up to 3 mm above it), not hooked at apex, 0.5–25 mm.

Marsilea vestita

Marsileaceae
Phenology Sporocarps produced spring–fall (Apr–Oct).
Habitat Widespread and variable, in ponds and wet depressions and on river floodplains
Elevation 0–2300 m (0–7500 ft)
Distribution
from FNA
AR; AZ; CA; CO; IA; ID; KS; LA; MN; MT; ND; NE; NM; NV; OK; OR; SD; TX; UT; WA; WY; AB; BC; SK; Mexico; South America in Peru
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Nearly worldwide; temperate and tropical regions
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Discussion

A number of segregate species have been named and recognized in regional floras in North America: Marsilea mucronata A. Braun (less hairy, found east of Rocky Mountains), M. uncinata (glabrous, sporocarp stalks long, distal tooth of sporocarp hooked, south central United States), M. tenuifolia (pinnae very narrow, central Texas), and M. fournieri (small plants and pinnae, southwest). The features upon which these species are based intergrade into one another. The species are therefore best treated as conspecific with M. vestita (D. M. Johnson 1986).

Putative hybrids between Marsilea macropoda and this species are discussed under the former.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Spore germination in the family occurs after rupture of the sporocarp wall allows the sporocarp contents to be hydrated. A gelatinous structure emerges from the sporocarp, breaking it into valves and carrying the sori into the water. Spore germination (gametophyte growth) and fertilization occur immediately.

Regnellidium diphyllum Lindman was introduced into a wildlife pond in Mahoning County, Ohio, in 1985 and continues to persist (C. F. Chuey, in litt. 1991). Regnellidium is similar to Marsilea but differs from it in having two leaflets instead of four.

Genera 3, species ca. 50 (2 genera, 7 species in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Leaves with blades palmately divided into 4 obdeltate or cuneate pinnae.
Marsilea
1. Leaves filiform, lacking expanded blades.
Pilularia
Source FNA vol. 2. FNA vol. 2, p. 331. Author: David M. Johnson.
Parent taxa Marsileaceae > Marsilea
Sibling taxa
M. ancylopoda, M. macropoda, M. mollis, M. oligospora, M. quadrifolia
Subordinate taxa
Marsilea, Pilularia
Synonyms M. fournieri, M. mucronata, M. tenuifolia, M. uncinata, M. vestita subsp. tenuifolia
Name authority Hooker & Greville: Icon. Filic. 2: plate 159. (1830) Mirbel
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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