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  • Hydrostachyaceae Engl.

This family is accepted.

[FTEA]

Hydrostachyaceae, B. Verdcourt. Flora of Tropical East Africa. 1986

Morphology Leaves
Leaves emergent or sometimes floating, often fern-like, borne in a rosette on the rhizome, developing when the water is low, dilated and ligulate at the base, at first small and entire, becoming large, entire, lobed or 2–3-pinnate, the petiole, rhachis and subdivisions covered with emergences of very diverse shape
Morphology Reproductive morphology Flowers
Flowers unisexual in dense spikes (synflorescence polytele), sometimes appearing precociously, usually when water low, each flower borne in the axil of a bract consisting of a distal and proximal part, the latter usually termed the spur (éperon) The ? flower reduced to a unilocular but 2-carpellate ovary; placentas 2, parietal with numerous anatropous tenuinucleate unitegmic ovules; styles 2, glabrous, erect or divergent The ? flower is reduced to a single stamen; anther with 2 divergent thecae dehiscing longitudinally; pollen in tetrads
Morphology Reproductive morphology Flowers Calyx
Sepals and petals absent
sex Male
The ? flower is reduced to a single stamen; anther with 2 divergent thecae dehiscing longitudinally; pollen in tetrads
Morphology Reproductive morphology Fruits
Fruit a small capsule enclosed by the bract, opening by 2 equal valves along the median suture, many-seeded, bearing the persistent styles
Morphology Reproductive morphology Seeds
Seeds ovoid, very light; endosperm cellular, divided into 3 parts but transitory, soon used by the developing embryo and ± nil in ripe seeds
Morphology General Habit
Partly submerged aquatic dioecious (but in one species monoecious, and another monoecious or dioecious) herbs with tuber-like rhizomes, sometimes stoloniferous, the roots attached to rocks in waterfalls and rapidly running water

[FZ]

Hydrostachyaceae, B.L. Stannard. Flora Zambesiaca 9:2. 1997

Morphology General Habit
Aquatic herbs attached to rocks in waterfalls and fast-flowing fresh water, usually dioecious, rhizomatous or sometimes stoloniferous
Vegetative Multiplication Rhizomes
Rhizomes discoid or tuberous; roots numerous, radiating
Morphology Leaves
Leaves submerged or emergent, basal, usually rosulate, often fern-like in appearance with a dorsal (abaxial) and ventral (adaxial) surface, 1–2-pinnate, 2–3-pinnatisect (entire or lobed), dilated and ligulate at the base; petiole and rhachis ± dorso-ventrally flattened and ± densely covered with wart-like or tongue-shaped outgrowths (emergences); pinnae (primary divisions of the leaf) numerous, subopposite, ± cylindrical in outline, bearing simple to variously divided emergences all around the pinna axis, sometimes also with secondary branches (pinnules)
Morphology Reproductive morphology Inflorescences
Inflorescences emergent, scapiform, densely spicate (resembling fruiting spikes of Plantago), produced as water level recedes; peduncle verrucose, rarely smooth or becoming so (on dried specimens at least) as emergences are shed
Morphology Reproductive morphology Flowers
Flowers unisexual, solitary in the axil of an enclosing bract, sessile; bracts spirally arranged, imbricate, differing in form between the sexes, distal part of bract variously margined or flanged, proximal part or spur [the éperon of Cusset] concave; sepals and petals absent Male flower reduced to a single subsessile stamen; anther thecae 2, dehiscing longitudinally Female flower reduced to a 2-carpellate unilocular ovary; ovules numerous, anatropous; styles 2, filiform, exserted from bracts, persistent on the fruit
sex Male
Male flower reduced to a single subsessile stamen; anther thecae 2, dehiscing longitudinally
sex Female
Female flower reduced to a 2-carpellate unilocular ovary; ovules numerous, anatropous; styles 2, filiform, exserted from bracts, persistent on the fruit
Morphology Reproductive morphology Fruits
Fruit a small capsule enclosed by the persistent bract, 2-valved
Morphology Reproductive morphology Seeds
Seeds small, numerous

Hydrostachyaceae Engl. appears in other Kew resources:

First published in Bot. Jahrb. Syst. 20(1-2): 136. 1894 [16 Nov 1894] (1894)

Accepted by

  • APG IV (2016) http://dx.doi.org/10.1111/boj.12385

Flora Zambesiaca
Flora Zambesiaca
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 Names and Taxonomic Backbone
The International Plant Names Index and World Checklist of Selected Plant Families 2021. 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