Common Name: WATERWEED FAMILY Habit: Annual, perennial herb, aquatic, freshwater or marine, glabrous or hairy; monoecious, dioecious, or flowers bisexual. Leaf: basal, alternate, opposite, or whorled, generally sessile, generally +- sheathing at base. Inflorescence: axillary, terminal, or scapose, cyme or flowers 1, subtended by +- sheathing, entire or lobed bract; staminate flowers sometimes deciduous, free-floating. Flower: generally radial; perianth 0 or tube 0 or elongate, peduncle-like in flower; sepals (0)3(4), green; petals (0)3(4), white or not; stamens (0)2--many, generally in 1+ series; ovary inferior, chamber 1 or falsely 6--9, placentas parietal, 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. Note:Ottelia alismoides (L.) Pers. is a possibly extirpated alien. eFlora Treatment Author: Robert F. Thorne, C. Barre Hellquist & Robert R. Haynes Scientific Editor: Thomas J. Rosatti.
NATURALIZED Habit: Perennial herb, rooting at nodes, submersed; dioecious. Stem: tuber-like; erect stems elongate, much-branched. Leaf: generally 4--8 per node, sessile, 1--2 cm, 1.5--2 mm wide, oblong, coarsely serrate, midrib prickled abaxially or not, tip generally sharp-pointed. Staminate Inflorescence: flower 1, bract at base of elongate perianth tube, spheric. Pistillate Inflorescence: flower 1, bract at base of elongate perianth tube, +- cylindric. Staminate Flower: deciduous, free-floating; perianth parts 6 in 2 whorls, 3--5 mm; stamens 3. Pistillate Flower: persistent, floating; perianth parts 6 in 2 whorls, 3--5 mm; stigmas 3. Fruit: 5--6 mm, +- fusiform. Chromosomes: 2n=32. Ecology: Canals, ponds, lakes; Elevation: < 200 m. Bioregional Distribution: NCoRI, n&c SNF, ScV, SCo, D; Distribution Outside California: southeastern and eastern United States, Central America; native to Eurasia, Australia. Flowering Time: Jun--Aug Jepson eFlora Author: Robert F. Thorne, C. Barre Hellquist & Robert R. Haynes Index of California Plant Names (ICPN; linked via the Jepson Online Interchange) Noxious Weed listed on the CDFA Weed Pest Ratings table View the CDFA Pest Rating page for Hydrilla verticillata Weed listed by Cal-IPC Previous taxon: Hydrilla Next taxon: Limnobium
Botanical illustration including Hydrilla verticillata
Citation for this treatment: Robert F. Thorne, C. Barre Hellquist & Robert R. Haynes 2012, Hydrilla verticillata, in Jepson Flora Project (eds.) Jepson eFlora, https://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=28595, accessed on April 18, 2024.
Citation for the whole project: Jepson Flora Project (eds.) 2024, Jepson eFlora, https://ucjeps.berkeley.edu/eflora/, accessed on April 18, 2024.
No expert verified images found for Hydrilla verticillata.
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(Note: any qualifiers in the taxon distribution description, such as 'northern', 'southern', 'adjacent' etc., are not reflected in the map above, and in some cases indication of a taxon in a subdivision is based on a single collection or author-verified occurence).
Data provided by the participants of the
Consortium of California Herbaria.
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CCH collections by month
Duplicates counted once; synonyms included.
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Blue line denotes eFlora flowering time (fruiting time in some monocot genera).
