Jepson Flora Project: Jepson Interchange    

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

HYDROCHARITACEAE

WATERWEED FAMILY

Robert F. Thorne

Annual, perennial herb, aquatic, freshwater or marine, bisexual, monoecious, or dioecious
Leaves basal or cauline, alternate, opposite, or whorled, generally ± sheathing at base, glabrous
Inflorescence: cyme; flowers 1–few, subtended by ± sheathing, entire or lobed bract; staminate flowers sometimes deciduous, free-floating
Flower radial; perianth tube 0 or much elongated, peduncle-like in flower; sepals (0)3, green; petals (0)3, colored or white; stamens (1)3–many, generally in 1+ series; ovary inferior, chamber 1, placentas parietal or basal, ovules 1–many; style lobes generally 3, linear, lobed or notched
Fruit: achene or berry-like and dehiscing irregularly, linear to spheric, submersed
Genera in family: ± 17 genera, ± 130 species: worldwide; some cultivated for aquaria, others noxious weeds.

ELODEA

Perennial, rooting at nodes, generally submersed, dioecious or some flowers bisexual
Stem slender, generally branched
Leaves opposite or whorled, generally 3 per whorl, sessile; blade margin minutely, finely toothed
Inflorescence: flowers solitary, axillary, sessile or peduncled; bract generally notched
Staminate flower floating, deciduous or not; perianth tube elongated, slender, peduncle-like; stamens 3–9
Pistillate flower floating; perianth tube elongated, slender, peduncle-like; style slender, stigmas 3, simple or 2-lobed
Fruit cylindric to ovoid
Seeds several
Species in genus: ± 12 species: temp and tropical Am
Etymology: (Greek: of marshes)
[St. John, 1965 Rhodora 67:1–35,155–180]

Native

E. nuttallii (Planch.) H. St. John

NUTTALL'S WATERWEED


Leaves generally not crowded at stem tips; middle and upper 3(4) per whorl; blade generally 6–13 mm, 0.3–1.5(2) mm wide, linear to narrowly lanceolate, tapered to acute tip
Staminate inflorescence: bract ovoid, abruptly pointed; flower deciduous, free-floating
Staminate flower: sepals ± 2 mm, ± 1.5 mm wide; petals generally 0 or ± 0.5 mm
Pistillate flower: sepals ± 1 mm
Seed short-soft-hairy
Chromosomes: 2n=48
Ecology: Shallow water, streams, lakes, ponds, ditches
Elevation: 500–2800 m.
Bioregional distribution: Klamath Ranges, High Sierra Nevada, Sacramento Valley, San Bernardino Mountains, Great Basin Floristic Province
Distribution outside California: to Washington, c US
Flowering time: Jul–Aug

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