According to Flora of Tropical East Africa[FTEA]
Potamogetonaceae, J.J. Symoens. Flora of Tropical East Africa. 2006
- Aquatic herbs, perennial or rarely annual, glabrous, rooted in the substrate
- Vegetative shoot system comprising horizontal shoots, mostly stoloniferous, non chlorophyllous (here called rhizomes) and vertical shoots, erect or sometimes ± floating, often densely branched, chlorophyllous (here called stems); tubers or turions sometimes present on the horizontal and/or the erect shoots
- Leaves alternate or subopposite, rarely ternate, sessile or petiolate, simple, served by 3 traces, parallel-veined or with a single midvein; stipules present throughout or only on young shoots ( Groenlandia ), often forming a tubular sheath around the stem and young inflorescence, either free or adnate to the base of the blade; intravaginal scales 2– several, situated in leaf axils, mostly linear to subulate, rarely ovate, entire and acute; bladeentire, denticulate or serrate
- Inflorescences pedunculate, with 2 opposite flowers ( >i>Groenlandia ) or more than 2 flowers in a dense or interrupted spike ( >i>Potamogeton ); peduncle rigid and mostly slightly elevated above the water level, but sometimes flexuous, the flowers resting then on the water surface, rarely submerged, but often withdrawing the fruits below the surface; bracts abortive or absent
- Flowers& #2695; (hermaphrodite), small, regular, hypogynous, tetramerous
- Perianth: a singlewhorl of 4 valvate shortly clawed tepals
- Stamens 4, opposite the tepals and basally adnate to the claw; anthers sessile, bilocular, extrorse, opening by longitudinal slits
- Gynoecium superior, of (1– 3) 4 (5– 8) carpels, sessile, free or shortly connate at the base, alternating with the stamens; styles usually short; stigma unicellular-papillate and strongly secretory or smooth and dry or weakly secretory; ovule solitary in the carpel and attached to its ventral margin, orthotropous at first, but becoming campylotropous at maturity, pendant and filling the locule, bitegmic, crassinucellate
- Fruit apocarpous consisting of distinct sessile fruitlets, ± drupaceous, but opening with a dorsal lid, with a rather fleshy parenchymatous mesocarp and a sclerified endocarp, the latter multi-layered ( >i>Potamogeton )or 1-layered ( >i>Groenlandia )
- Seed without endosperm; embryo unciform or spiral (i.e. coiled more than 1 complete turn), with a large hypocotyl and a single obliquely terminal cotyledon that encloses the plumule
According to Neotropikey[NTK]
Haigh, A. (2009). Neotropical Potamogetonaceae.
Aquatic freshwater or brackish herbs, typically perennial or annual (Zannichellia L.), rooted in the substrate with rhizomes or stolons sometimes; upper stems erect , ± reaching water surface. Leaves alternate , opposite or in pseudo-whorls, simple ; submersed leaves present in all species (although sometimes decayed), these petiolate or sessile , floating leaves present in some species, these nearly always petiolate ; "stipular" sheath always present, distinct from petioles or blades (floating leaves) or occasionally adnate (submersed leaves); distinct ligule usually present when stipular sheath distinct; blade shape similar or dissimilar in floating and submersed leaves of same plant, expanded (in floating leaves and in most petiolate and occasionally sessile submersed leaves) or linear (many submersed sessile leaves), sometimes filiform (Zannichellia), flattened without groove along one side (Potamogeton L.) or semiterete with channel or groove along one side (Stuckenia Börner); cuticle evident on adaxial surface of floating leaves, absent in submersed leaves. Inflorescences terminal or axillary , spikes or of 1 staminate and 1 pistillate flower per axil (Zannichellia, both flowers with short pedicels), the terminal spikes usually emersed or floating on the surface, the axillary spikes usually submersed, rarely with both emersed and submersed spikes on same plant; peduncles sometimes present, then rigid (Potamogeton having considerable supporting tissue) allowing for emersion or non-rigid and never emersed (Stuckenia, this sometimes resulting in spikes lying at water surface); spikes consisting of 1-20+ flower whorls, the flowers mostly 3 per whorl. Flowers actinomorphic , bisexual or unisexual (Zannichellia). Bisexual flowers (Potamogeton, Stuckenia) with 4 clawed tepals; androecium of 4 stamens, the filaments each adnate to tepal claw , the anthers extrorse; gynoecium apocarpous, the ovaries superior , the carpels 4, styles short, stigmas capitate ; placentation marginal , 1 ovule per carpel . Staminate flowers (Zannichellia) located in same leaf axil and directly behind pistillate flowers; androecium of 1 stamen , filament to 3 cm long, anther directly above stigmas. Pistillate flowers (Zannichellia) with perianth fused into a tube; gynoecium apocarpous, ovaries superior , carpels 1-8, surrounded basally by perianth , stigmas funnel-shaped, exserted from perianth tube; placentation apical, 1 pendulous ovule per carpel . Fruits drupelets; seeds 1 per fruit ; embryo coiled or curved.
Distribution in the Neotropics
A family of 4-7 genera depending on generic and familiar circumscriptions adopted, and c. 90-95 species (an additional 40-50 putative hybrids of many Potamogeton have been described), occurring in fresh and brackish waters worldwide. Three genera comprising c. 22 species occur in the Neotropics.
- Potamogeton: about 80 species worldwide, with ca. 17 species of these occurring in the Neotropics.
- Stuckenia: about four species subcosmopolitan, three species occur in the Neotropics.
- Zannichellia: about five species near cosmopolitan, with two species in the Neotropics.
Distinguishing characters (always present)
- Aquatic herbs.
- Leaves simple (submersed or floating).
- Fruits drupes.
- Inflorescences usually spikes, terminal or axillary.
- Stipular sheath usually present.
- General Description
- Native: some species are endemic.
- Potamogetonaceae is placed in the Alismatales, most closely related to Zosteraceae.
- Zannichellia is rather weakly embedded in the Potamogetonaceae but placed here in APG II.
- Fruits provide the most important features in separating species of this family; consequently one should always collect fruiting specimens.
- Some species are important foods for waterfowl and are also grown in aquaria.
- Environmentally some species are very important in substrate stabilization and in removing particles from the water column.
Haynes, R.R., 2004. Potamogetonaceae. Pp. 476-477. In: Smith, N., Mori, S.A., Henderson, A., Stevenson, D.W. & Heald, S.V. (eds.). Flowering Plants of the Neotropics. New York Botanical Garden, Princeton University Press, Princeton.
Haynes, R.R., 2004. Zannichelliaceae. Pp. 493-494. In: Smith, N., Mori, S.A., Henderson, A., Stevenson, D.W. & Heald, S.V. (eds.). Flowering Plants of the Neotropics. New York Botanical Garden, Princeton University Press, Princeton.
Haynes, R.R., Les, D.H. & Holm-Nielsen L.B., 1998. Potamogetonaceae. In: K. Kubitzki (ed.), The families and genera of vascular plants 4: 408-415. Springer Verlag, Berlin, Heidelberg, New York.
Haynes, R.R., Les, D.H. & Holm-Nielsen L.B., 1998. Zannichelliaceae. In: K. Kubitzki (ed.), The families and genera of vascular plants 4: 470-474. Springer Verlag, Berlin.Stevens, P. F. (2008). Angiosperm Phylogeny Website. Version 9 onwards. http://www.mobot.org/MOBOT/research/APweb/.
According to Flora of West Tropical Africa[FWTA]
Potamogetonaceae, F.N. Hepper. Flora of West Tropical Africa 3:1. 1968
- Aquatic herbs of fresh, water
- Leaves alternate or opposite, those immersed thin, those above water often leathery, sheathing at the base, sheath free or partially adnate to the petiole
- Flowers hermaphrodite, small, arranged in pedunculate axillary spikes; peduncle surrounded by a sheath at the base; bracts absent
- Perianth of 4 free rounded shortly clawed valvate segments
- Stamens 4, inserted in the claws of the segments; anthers extrorse, 2-locular, sessile
- Carpels 4, free, 1-locular; stigmas sessile or on short styles; ovule solitary, on the adaxial angle
- Fruits free, 1-seeded, indehiscent
- Seeds without endosperm
According to Flora of Tropical East Africa under the synonym Zannichelliaceae[FTEA]
Zannichelliaceae, H. J. Beentje, M.Sc., Ph.D., F.L.S.. Flora of Tropical East Africa. 2000
- Submerged aquatics of fresh or brackish water, monoecious; rhizomes with unbranched roots; stems branched
- Leaves spirally arranged or distichous, sometimes appearing whorled or subopposite; sheath amplexicaul; blade linear, 1(–3)-veined
- Flowers small, terminal in complex sympodial inflorescences; petals absent or scale-like and basally connate; anthers 1 (or several with thecae united), with 1 or more longitudinal slits; ovaries 1–5(–8), surrounded by a perianth-like structure, each with short style; ovules 1 per ovary, apical and pendulous
- Fruit a dense group of achenes or drupelets, the wall 2-layered, the inner wall persisting; endosperm absent
According to Flora of West Tropical Africa under the synonym Zannichelliaceae[FWTA]
Zannichelliaceae, F.N. Hepper. Flora of West Tropical Africa 3:1. 1968
- Submerged aquatic herbs in fresh, brackish, or salt water; rhizome creeping, slender
- Leaves alternate or opposite, or crowded at the nodes, linear, sheathing at the base, sheaths mostly ligulate at the apex; flowering leaves sometimes reduced to sheaths
- Flowers minute, monoecious or dioecious, axillary, solitary or in cymes
- Perianth of 3 small free scales, or absent
- Stamens 3, 2 or 1; anthers 2-1-locular, opening lengthwise; pollen globose or thread-like
- Ovule solitary, pendulous Carpels 1-9, free; style simple or 2-4-lobed
- Fruits sessile or stipitate, indehiscent
- Seed pendulous, without endosperm
First published in Prir. Rostlin Aneb. Rostl. 1(Sig. 7*-13): 1, 3. 1823 (as "Potamogetinae") (1823)
- APG IV (2016) http://dx.doi.org/10.1111/boj.12385
Flora of Tropical East Africa
Flora of Tropical East Africa
Flora of West Tropical Africa
Flora of West Tropical Africa
Kew Names and Taxonomic Backbone
The International Plant Names Index and World Checklist of Selected Plant Families 2018. 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
Milliken, W., Klitgard, B. and Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics.