Class
Classification
Subordinate Taxa
Nomenclature
Scientific Name:
Alismataceae Vent., Tabl. Regn. Vég. 2, 157 (1799)
Type Taxon:
Description
Aquatic (freshwater) emergent or floating-leaved herbs, perennial or annual (rarely), with milky sap; rhizomatous or stoloniferous; vessels absent. Roots adventitious, fibrous. Hermaphrodite, monoecious, polygamomonoecious, or dioecious (rarely). Leaves basal, sheathing, simple, petiolate or sessile, floating, often heterophyllous. Leaf-lamina lobed or non-lobed, margin entire, an apical pore present; venation reticulate, prominent primary veins parallel, secondary veins reticulate. Inflorescence a whorled scape, raceme, panicle, umbel (rarely) or solitary, bracteate, erect or rarely floating. Flowers perfect or imperfect, actinomorphic; perianth hypogynous in two alternate whorls, sepals 3 persistent, petals 3 deciduous. Androecium 0–6–9 to many stamens in 1 or more whorls, free; anthers tetrasporangiate, 2-loculed, basifixed or versatile, extrorse or latrose dehiscence, opening by longitudinal slits; pollination syndrome entomophilous. Gynoecium 0–3–6 to many, ovary superior; carpels free or united at base, in 1 whorl or spiralled, apocarpic or occasionally with two anatropous ovules, or many (Hydrocleys), placentation basal or laminar, styles apical or lateral, persistent; carpel nectariferous region or septal nectaries present. Fruit a single whorl of laterally compressed achenes (forming a ring or cluster), or a follicle. Seeds uncinate-curved, with a horseshoe-shaped embryo, non-endospermic; starch.
Taxonomy
Alismataceae is part of a group of families known as the alismatids, a large radiation of plants exhibiting numerous adaptations for life in water, both fresh and marine. This treatment follows Les & Tippery (2013) by including Hydrocleys in the Alismataceae, giving a total of about 113 species of herbs in 17 genera. The latter genus was previously placed by Healy & Edgar (1980) in the Butomaceae and by some recent floras in the Limnocharitaceae (Haynes & Holm-Neilsen 1992, Jacobs & McColl 2011).
Based on molecular phylogenies (Les & Cleland 1997, Iles et al. 2013, Ross et al. 2016) the Alismataceae are placed in a well-supported clade known as the ‘petaloid clade’, also including Butomaceae and Hydrocharitaceae; this clade is recognised by Les & Tippery (2013) at the ordinal level as the Alismatales, with its sister clade the ‘tepaloid clade’ named Potamogetonales Dumort. (= Zosterales Nakai).
Key
| 1 | Flowers unisexual | Sagittaria |
| 1' | Flowers bisexual | 2 |
| 2 | Inflorescence an erect, whorled panicle, corolla pale pink or lilac | Alisma |
| 2' | Inflorescence a lax scape, appearing solitary on long peduncles, corolla yellow | Hydrocleys |
Recognition
Plants have milky sap, the flowers are petaloid, and the petals are crumpled in bud and delicate. The seeds are uncinate-curved, with the embryo strongly bent to a horseshoe shape.
Distribution
Pantropical, temperate; almost cosmopolitan (Haynes & Holm-Neilsen 1992, Haynes & Holm-Neilsen 1994, Wang et al. 2010); 113 species in 17 genera (Les & Tippery 2013).
Biostatus
Exotic
| Category | Number |
|---|---|
| Exotic: Fully Naturalised | 6 |
| Total | 6 |
Bibliography
Cronquist, A. 1988: The evolution and classification of flowering plants. The New York Botanic Gardens, New York.
Ford, K.A.; Champion, P.D. 2020: Alismataceae. In: Wilton, A.D. (ed.) Flora of New Zealand - Seed Plants. Fascicle 7. Manaaki Whenua Press, Lincoln.
Haynes, R.R.; Holm-Neilsen, L.B. 1992: The Limnocharitaceae. In: Flora Neotropica. Vol. 56. New York Botanical Garden Press. 1–32.
Haynes, R.R.; Holm-Neilsen, L.B. 1994: The Alismataceae. In: Flora Neotropica. Vol. 64. New York Botanical Garden Press. 1–112.
Iles, W.J.D.; Smith, S.Y.; Graham, S.W. 2013: A well supported phylogenetic framework for the monocot order Alismatales reveals multiple losses of the plastid NADH dehydrogenase complex and a strong long-branch effect. In: Wilkin, P.; Mayo, S.J. (ed.) Early Events in Monocot Evolution. Cambridge University Press, Cambridge, UK. 1–28.
Jacobs, S.W.L.; McColl, K.A. 2011: Limnocharitaceae. In: Wilson, A.J.G. (ed.) Flora of Australia. Vol. 39. ABRS/CSIRO, Melbourne.
Les, D.H.; Cleland, M.A. 1997: Phylogenetic Studies in Alismatidae, II: Evolution of Marine Angiosperms (Seagrasses) and Hydrophily. Systematic Botany 22(3): 443–463.
Les, D.H.; Tippery, N.P. 2013: Evolution of alismatid aquatics. In: Wilkin, P.; Mayo, S.J. (ed.) Early Events in Monocot Evolution. Cambridge University Press, Cambridge, UK.
Mabberley, D.J. 2008: Mabberley's plant book, a portable dictionary of plants, their classification and uses. Edition 3. Cambridge University Press.
Ross, T.G.; Barrett, C.F.; Gomez, M.S.; Lam, V.K.Y.; Henriquez, C.L.; Les, D.H.; Davis, J.I.; Cuenca, A.; Petersen, G.; Seberg, O.; Thadeo, M.; Givnish, T.J.; Conran, J.; Stevenson, D.W.; Graham, S.W. 2016: Plastid phylogenomics and molecular evolution of Alismatales. Cladistics 32: 160–187.
Ventenat, E.P. 1799: Tableau du Règne Végétal, Selon de Méthode de Jussieu. Paris. Vol. 2. J. Drisonnier, Paris.
Wang, Q.; Haynes, R.R.; Hellquist, C.B. 2010: 4. Alismataceae. In: Flora of China (Acoraceae through Cyperaceae). Vol. 23. In: Wu, C.Y.; Raven, P.H.; Hong, D.Y. (ed.) Flora of China. Science Press, Beijing, and Missouri Botanical Garden Press, St. Louis.
