|Jepson Flora Project: Jepson Interchange|
|TREATMENT FROM THE JEPSON MANUAL (1993)||
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Jepson Interchange (more information)
©Copyright 1993 by the Regents of the University of California
AND IS MAINTAINED FOR ARCHIVAL PURPOSES ONLY
Plant free-floating or stranded on mud, generally 15 cm, often fan-shaped; roots pendent from stem forks, unbranched
Stem forked repeatedly or pinnate, thread-like, easily fragmented at joints
Leaves alternate, in 2 rows, sessile, often overlapped, 0.51.5 mm, seemingly paired but actually of 2 roundish to ovate lobes; upper lobe floating or emergent, thick, greenish or reddish, margin whitish; lower lobe submersed, generally slightly larger, thinner, whitish
Sporangia in seemingly axillary cases of 2 kinds, cases generally in pairs of 1 kind
Male sporangium case 1.22 mm diam, spheric; tip dark-pointed; wall transparent; sporangia generally 20100+, long-stalked; spores 32 or 64, spheric, in generally 36 barbed masses
Female sporangium case 0.20.4 mm diam, hemispheric or spheric; tip obtuse, covered by dark, conic, spongy structures that aid in flotation; wall ± opaque; sporangium 1, sessile; spore 1, spheric
Genera in family: 1 genus, ± 7 species: ± worldwide. Salvinia molesta D.S. Mitch. has been tentatively identified from Walter's Camp, Imperial Co.; more study needed.
Etymology: (Greek: dry kill, from plant death in dried habitats)
Reference: [Perkins et al. 1985 Scanning Electron Microscopy 1985(IV):17191734]
Used as green manure in rice paddies because of nitrogen-fixing algae in upper leaf lobe; species identification requires generally female sporangium cases (generally 0 on herbarium specimens), often leaf sectioning, compound microscope.
Plant green to reddish, fertile only when ascending
Stems < 5+ cm: immature prostrate, internodes < 5 mm; mature ascending, internodes < 1 mm
Sporangium cases generally male
Ecology: Common. Ponds, slow streams, wet ditches
Elevation: 01600 m.
Bioregional distribution: California Floristic Province, Great Basin Floristic Province
Distribution outside California: to Washington, Arizona, S.America, Eurasia, Africa; also e US
Horticultural information: still water [not saline] or mud: 4, 5, 6, 7, 8, 9, 10, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24.