Jepson eFlora: Taxon page
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Hydrilla verticillata

Higher Taxonomy
Family: HydrocharitaceaeView DescriptionDichotomous Key

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.
Genus: HydrillaView Description 


Species In Genus: 1 sp. Etymology: (Greek: in water)

Hydrilla verticillata (L. f.) Royle
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
eFlora Treatment Author: Robert F. Thorne, C. Barre Hellquist & Robert R. Haynes
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Noxious Weed

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botanical illustration including Hydrilla verticillata

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Citation for this treatment: Robert F. Thorne, C. Barre Hellquist & Robert R. Haynes 2016. Hydrilla verticillata, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=28595, accessed on May 02, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on May 02, 2016.


Geographic subdivisions for Hydrilla verticillata:
NCoRI, n&c SNF, ScV, SCo, D;
Markers link to CCH specimen records. If the markers are obscured, reload the page [or change window size and reload]. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues.
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map of distribution 1
(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).

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Data provided by the participants of the Consortium of California Herbaria.
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CCH collections by month

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa.
Blue line denotes eFlora flowering time.