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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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.

SPIRODELA

DUCKMEAT

Plants generally in clusters of 2–5; roots 1–16, some passing through minute scale on lower surface
Plant body 3–10 mm, oblong to round, flat; upper surface dark shiny green, lower generally red-purple; veins 3–12 (visible in backlight); young plants with minute scale-like leaf on each side at base; winter buds often produced
Flowers in 2 lateral budding pouches, sheathed by minute membrane
Seed ribbed
Species in genus: 3 species: worldwide
Etymology: (Greek: visible thread, from roots)

Native

S. polyrrhiza (L.) Schleid.

Roots 5–16, 1–2 passing through minute scale
Plant body 5–10 mm, round-ovate, symmetric; veins 7–12; upper surface smooth; winter buds produced in autumn
Ecology: Freshwater
Elevation: 0–2500 m.
Bioregional distribution: California
Distribution outside California: nearly worldwide
Flowering time: Aug

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bioregional map for SPIRODELA%20polyrrhiza being generated
 
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Retrieve Jepson Interchange Index to Plant Names entry for Spirodela polyrrhiza
Retrieve dichotomous key for Spirodela
Overlay Consortium of California Herbaria specimen data by county on this map
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