Family:
Hydrocharitaceae Juss.

Hydrilla Rich.

This genus is accepted, and its native range is E. Europe to Asia, Australia, Uganda to N. Zambia.

[FTEA]

Hydrocharitaceae, David Simpson. Flora of Tropical East Africa. 1989

Morphology General Habit
Monoecious, rarely dioecious, submerged, freshwater, annual or perennial herbs
Vegetative Multiplication Bulbils
Plants often perennating by turions, the turions bulbil-like, arising from tip of stolons or in leaf-axils
Morphology Roots
Roots simple, adventitious, without root-hairs, arising from nodes
Morphology Stem
Stems elongate, stoloniferous, or erect, terete, simple or branched from axils; branches 1 per axil
Morphology Leaves
Leaves sessile, opposite towards base of stem or branch, otherwise in whorls of 3–8(–12), linear to ovate, shortly acuminate to obtuse, patent, spreading or strongly recurved, flaccid, light to dark green, opaque or somewhat translucent, with 1 apical spine; margins hyaline, denticulate, the teeth usually patent; venation consisting of midrib only Nodal scales 2 per leaf, narrowly triangular to narrowly lanceolate, fringed with orange-brown hairs
Morphology Leaves Stipules
Stipules 0
Morphology Reproductive morphology Flowers
Flowers unisexual Female flower: sepals 3, free, oblong to ovate, somewhat cucullate, erect; petals 3, free, oblong to ovate, obtuse, erect; staminodes 3, minute, linear or absent; ovary of 3 carpels, 1-locular, placentation parietal; ovules up to 5, anatropous; perianth-tube filiform, carrying perianth to the water surface; styles 3; stigmas 3, linear, usually entire, rarely bifid, papillose Male flowers shortly pedicellate, becoming detached and floating before anthesis; sepals 3, ovate, obtuse, reflexed at anthesis; petals 3, linear to ± spathulate, obtuse, ± reflexed at anthesis; stamens 3, anthers erect, 4-thecous, dehiscing explosively; filaments filiform
Morphology Reproductive morphology Inflorescences
Male spathe solitary in leaf-axil, sessile, appendages at the apex, 1-flowered Female spathes 1(–2) in leaf-axil, sessile, cylindric but tapering toward apex, 1-flowered
sex Male
Male spathe solitary in leaf-axil, sessile, appendages at the apex, 1-flowered Male flowers shortly pedicellate, becoming detached and floating before anthesis; sepals 3, ovate, obtuse, reflexed at anthesis; petals 3, linear to ± spathulate, obtuse, ± reflexed at anthesis; stamens 3, anthers erect, 4-thecous, dehiscing explosively; filaments filiform
sex Female
Female flower: sepals 3, free, oblong to ovate, somewhat cucullate, erect; petals 3, free, oblong to ovate, obtuse, erect; staminodes 3, minute, linear or absent; ovary of 3 carpels, 1-locular, placentation parietal; ovules up to 5, anatropous; perianth-tube filiform, carrying perianth to the water surface; styles 3; stigmas 3, linear, usually entire, rarely bifid, papillose Female spathes 1(–2) in leaf-axil, sessile, cylindric but tapering toward apex, 1-flowered
Morphology Reproductive morphology Fruits
Fruit cylindric, smooth or with lateral spine-like appendages
Morphology Reproductive morphology Seeds
Seeds up to 5, narrowly ellipsoid, smooth.

Native to:

Afghanistan, Altay, Amur, Assam, Baltic States, Bangladesh, Belarus, Borneo, Burundi, Cambodia, China North-Central, China South-Central, China Southeast, East Himalaya, Hainan, India, Iran, Irkutsk, Japan, Jawa, Kazakhstan, Kenya, Khabarovsk, Korea, Krasnoyarsk, Lesser Sunda Is., Malaya, Maluku, Manchuria, Myanmar, Nansei-shoto, Nepal, New Guinea, New South Wales, Northern Territory, Northwest European R, Pakistan, Philippines, Primorye, Queensland, Rwanda, South Australia, Sri Lanka, Sulawesi, Sumatera, Taiwan, Tanzania, Thailand, Tibet, Uganda, Victoria, Vietnam, West Himalaya, West Siberia, Western Australia, Zambia, Zaïre

Introduced into:

Alabama, Arizona, Aruba, California, Canary Is., Colombia, Connecticut, Costa Rica, Cuba, Delaware, District of Columbia, Fiji, Florida, Georgia, Germany, Ghana, Great Britain, Honduras, Indiana, Ireland, Ivory Coast, Jamaica, Kansas, Kentucky, Leeward Is., Louisiana, Madagascar, Maine, Marianas, Maryland, Massachusetts, Mauritius, Mexico Northeast, Mississippi, Missouri, Mozambique, New Caledonia, New York, New Zealand North, Nicaragua, North Carolina, Ohio, Oregon, Panamá, Pennsylvania, Réunion, South Carolina, Tennessee, Texas, Trinidad-Tobago, Venezuela, Virginia, Washington, West Virginia, Windward Is.

Hydrilla Rich. appears in other Kew resources:

Date Reference Identified As Barcode Type Status Has image?
s.coll. [Cat. no. 7488] Serpicula K001127396 Yes

First published in Mém. Cl. Sci. Math. Inst. Natl. France 12(2): 9 (1811 publ. 1814)

Accepted by

  • Govaerts, R.H.A. (2011). World checklist of selected plant families published update Facilitated by the Trustees of the Royal Botanic Gardens, Kew.

Literature

Flora of Tropical East Africa

  • Cook & Lüönd in Aquat. Bot. 13: 485 (1982)
  • Wright in F.T.A. 7: 1 (1897)
  • in Mém. Cl. Sci. Math. Phys. Inst. France 1811(2): 9, 61, 69, 75 (1812, published 1814)

  • Flora of Tropical East Africa

    Flora of Tropical East Africa
    http://creativecommons.org/licenses/by-nc-sa/3.0

  • Herbarium Catalogue Specimens

    Digital Image © Board of Trustees, RBG Kew http://creativecommons.org/licenses/by/3.0/

  • Kew Backbone Distributions

    The International Plant Names Index and World Checklist of Selected Plant Families 2022. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
    © Copyright 2017 World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0

  • Kew Names and Taxonomic Backbone

    The International Plant Names Index and World Checklist of Selected Plant Families 2022. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
    © Copyright 2017 International Plant Names Index and World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0