Jepson Flora Project: Jepson Interchange    

 
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Jepson Interchange (more information)
©Copyright 1993 by the Regents of the University of California

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  • Up-to-date information about California vascular plants is available from the Jepson eFlora.

LEMNACEAE

DUCKWEED FAMILY

Wayne P. Armstrong

Perennial, floating aquatics, small, clonal, in dense populations; new plants produced in budding pouch at base or along margins; may overwinter on bottom as dense, rootless, starch-filled daughter plant (winter bud); roots 0–many
Plant body 0.4–10 mm, flat and tongue-shaped to spheric
Flower 1, rarely seen, minute, appearing like 2–3 unisexual flowers, often sheathed by minute membrane; perianth 0; stamens 1–2; pistil 1, simple, maturing before stamens
Fruit achene-like, sometimes winged
Seeds 1–3, smooth or ribbed. Spp. best separated by chemistry and fruit; clones vary; magnification, backlighting generally needed to identify vegetative plants
Genera in family: 4 genera, 34 species: worldwide; ornamental in pools, aquaria
Reference: [Landolt 1986 Veröff Geobot Inst ETH Stiftung Rübel Zürich 71]
Horticultural information: TRY.

LEMNA

DUCKWEED

Plants generally in clusters of 2–many; root generally 1, generally 2–6 mm, sheath near base generally not winged
Plant body generally 2–5 mm, flat, generally widely elliptic to oblong, pale to dark green, often ± red; veins 1–5 (visible in backlight); winter buds generally 0
Flowers in 2 lateral pouches, sheathed by minute membrane
Fruit generally unwinged
Seed ribbed, generally smooth between ribs
Species in genus: 13 species: worldwide
Etymology: (Greek: lake or swamp)

Native

L. valdiviana Phil.


Plant bodies often in clusters of 4–8, 2–4 mm, thin, elliptic to narrowly oblong, uniformly transparent green; base often asymmetric; tip symmetric; surfaces smooth; vein up to 3/4 distance from root node to tip of plant body (generally > region of visible air spaces between cells)
Seed cross-lined between ribs
Ecology: Freshwater
Elevation: < 1500 m.
Bioregional distribution: North Coast, North Coast Ranges, Central Western California, South Coast
Distribution outside California: to e US, S.America
Synonyms: L. cyclostasa (Elliott) C. Thompson, not Chevall
Variable. Apparently uncommon in CA, especially in mtns. Forms tangled masses under other plants.

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bioregional map for LEMNA%20valdiviana being generated
 
N.B. The distribution depicted here differs from that given in The Jepson Manual (1993)

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