Family:
Hydrocharitaceae Juss.

Thalassia Banks & Sol. ex K.D.Koenig

This genus is accepted, and its native range is Tropical & Subtropical coasts.

[FSOM]

M. Thulin. Flora of Somalia, Vol. 1–4 [updated 2008] https://plants.jstor.org/collection/FLOS

Distribution
Genus of two similar species, T . testudinum Banks ex König in the Caribbean and T. hemprichii (Ehrenb.) Aschers. in the Indian Ocean and the western Pacific.
Morphology General Habit
Dioecious perennials; rhizomes creeping, scale-bearing and with extended internodes, giving rise at regular intervals to erect, short, leafy shoots; older erect shoots partially enclosed by persistent remains of leaf bases; roots one per node, unbranched, conspicuously septate, covered with sand-binding, fine hairs
Morphology Leaves
Leaves usually 2–6, distichously arranged, linear or falcate, distinctly sheathing at the base; veins 9–17, connected by cross-veins
Morphology Reproductive morphology Inflorescences
Inflorescences pedunculate, 1-flowered, in the axils of the leaves, 1–2 in male plants, 1 in female plants
Morphology Reproductive morphology Inflorescences Bracts Spathe
Spathal leaves united on one side only in male plants and on both sides in female ones, margins entire or serrulate
Morphology Reproductive morphology Flowers
Female flower subsessile; tepals 3; ovary of 6–8 carpels; styles 6–8, each with 2 filiform stigmas 2–6 times as long as the style Male flower shortly pedicellate; tepals 3, strongly recurved at anthesis; stamens 3–12; anthers subsessile, oblong, erect, 2–4-celled, latrorsely dehiscent; pollen grains spherical, stuck together into moniliform chains
Morphology Reproductive morphology Fruits
Fruit globose, beaked, echinate, split open at the top by stellate dehiscence of the fleshy pericarp into a number of irregular valves
Morphology Reproductive morphology Seeds
Seeds with a thickened basal portion.

[FTEA]

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

Morphology General Habit
Dioecious, submerged, marine, perennial herbs
Morphology Stem
Stem elongate, rhizomatous or shortly erect, the latter produced at regular intervals from nodes along the rhizome
Morphology Roots
Roots 1 per node where erect stems produced from the rhizome, simple, sand-binding, covered with fine hairs
Morphology Leaves
Leaves sessile, usually 2–6, distichously arranged on the erect stems, linear, somewhat falcate, rounded or obtuse, distinctly sheathing at the base, opaque or somewhat translucent, with up to 19 longitudinal veins and numerous fine, longitudinal air channels, the longitudinal veins connected by cross-veins; margins green, entire Nodal scales 0
Morphology Leaves Stipules
Stipules 0
Morphology Reproductive morphology Flowers
Flowers unisexual Female flowers almost sessile; tepals 3, similar to the those of ♂; staminodes 0; ovary of 6–8 carpels, conical, muricate, 1(–3)-locular, placentation parietal; ovules several; perianth-tube narrowly cylindric; styles 6–8; stigmas 6–8, deeply 2-lobed, filiform, papillose Male flowers shortly pedicellate, remaining attached to the plant; tepals 3, elliptic, cucullate, strongly recurved at anthesis; stamens 3–12; anthers nearly sessile, oblong, erect, 2–4-thecous, latrorsely dehiscent
sex Male
Male spathes 1–2 in the leaf-axil, pedunculate, 1-flowered, composed of 2 bracts connate on one side only, the bracts oblong to lanceolate, acute to obtuse, entire or serrulate, translucent Male flowers shortly pedicellate, remaining attached to the plant; tepals 3, elliptic, cucullate, strongly recurved at anthesis; stamens 3–12; anthers nearly sessile, oblong, erect, 2–4-thecous, latrorsely dehiscent
Morphology Reproductive morphology Inflorescences
Female spathe solitary in the leaf-axil, pedunculate, 1-flowered, composed of 2 connate bracts, cylindric, but tapering at both ends, translucent, 2-lobed at the apex, the lobes acute to obtuse Male spathes 1–2 in the leaf-axil, pedunculate, 1-flowered, composed of 2 bracts connate on one side only, the bracts oblong to lanceolate, acute to obtuse, entire or serrulate, translucent
sex Female
Female flowers almost sessile; tepals 3, similar to the those of ♂; staminodes 0; ovary of 6–8 carpels, conical, muricate, 1(–3)-locular, placentation parietal; ovules several; perianth-tube narrowly cylindric; styles 6–8; stigmas 6–8, deeply 2-lobed, filiform, papillose Female spathe solitary in the leaf-axil, pedunculate, 1-flowered, composed of 2 connate bracts, cylindric, but tapering at both ends, translucent, 2-lobed at the apex, the lobes acute to obtuse
Morphology Reproductive morphology Fruits
Fruit globose, beaked, densely hairy, opening by stellate dehiscence of the carpels
Morphology Reproductive morphology Seeds
Seeds conical with a thickened basal portion.

Native to:

Alabama, Aldabra, Andaman Is., Aruba, Bahamas, Belize, Bermuda, Bismarck Archipelago, Borneo, Caroline Is., Cayman Is., Cocos (Keeling) Is., Colombia, Comoros, Costa Rica, Cuba, Djibouti, Dominican Republic, Egypt, Eritrea, Florida, Gilbert Is., Guatemala, Hainan, Haiti, Honduras, India, Jamaica, Jawa, Kenya, Laccadive Is., Leeward Is., Lesser Sunda Is., Louisiana, Madagascar, Malaya, Maldives, Maluku, Marianas, Marshall Is., Mexico Gulf, Mexico Northeast, Mexico Southeast, Mozambique, Myanmar, Nansei-shoto, Netherlands Antilles, New Caledonia, New Guinea, Nicaragua, Nicobar Is., Northern Territory, Panamá, Philippines, Puerto Rico, Queensland, Saudi Arabia, Seychelles, Solomon Is., Somalia, South China Sea, Southwest Caribbean, Sri Lanka, Sudan, Sulawesi, Sumatera, Taiwan, Tanzania, Texas, Thailand, Trinidad-Tobago, Turks-Caicos Is., Venezuela, Venezuelan Antilles, Vietnam, Western Australia, Windward Is., Yemen

Thalassia Banks & Sol. ex K.D.Koenig appears in other Kew resources:

First published in Ann. Bot. (König & Sims) 2: 96 (1805)

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 Somalia

  • Flora Somalia, Vol 4, (1995) Author: by G. Sartoni [updated by M. Thulin 2008]

Flora of Tropical East Africa

  • Ann. Bot. 2: 96 (1805)
  • G.P. 3: 455 (1883)
  • Hartog, Sea Grasses of the World: 222 (1970)

  • Flora of Somalia

    Flora of Somalia
    http://creativecommons.org/licenses/by-nc-sa/3.0

  • Flora of Tropical East Africa

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