Inflorescence a panicle, or sometimes an umbell or solitary flowers. Emergent cordate or sagitate leaves. Aquatic herbs growing in marshes or living submerged, rooting in the bottom. Nectar secretions are present at the basal part of the carpels and sometimes the tepals and stamen bases are nectariferous as well (Echinodorus) Leaves basal, sessile or petiolate, simple, usually having a long sheath, sometimes pellucid punctate, margin usually entire; inflorescences usually erect, basally inserted, simple or compound, racemose, paniculate or sometimes umbellate: flowers bisexual or unisexual (plants then monoecious or rarely dioecious) tepals 6 in two rows, greenish or withis, stamens 3-6-9 numerous, ovary superior, of 6-numerous, free, unilocular carpels; Fruits, Achenes or rarely follicles, usually numerous, sometimes longitudinally costate, agregated in an infrutescence, seeds 1-several.
Alismataceae are laticiferous, aquatic herbs. Their floating or aerial leaves are petiolate and have a prominent midrib, parallel veins and also cross veins. Their petals are crumpled in bud and their staminate flowers usually have many extrorse anthers and their carpellate flowers have many free carpels. It is obvious from looking at the seeds that the embryo is strongly bent. (APG II website, 6.5.2009)
Distribution
Worldwide, but primarily in temperate and tropical regions of the northern hemisphere. Cosmopolite
Floral characters
Inflorescence a panicle, or sometimes an umbell or solitary flowers. Nectar secretions are present at the basal part of the carpels and sometimes the tepals and stamen bases are nectariferous as well (Echinodorus) inflorescences usually erect, basally inserted, simple or compound, racemose, paniculate or sometimes umbellate: flowers bisexual or unisexual (plants then monoecious or rarely dioecious) tepals 6 in two rows, greenish or withis, stamens 3-6-9 numerous, ovary superior, of 6-numerous, free, unilocular carpels
Leaf characters
Emergent cordate or sagitate leaves. Aquatic herbs growing in marshes or living submerged, rooting in the bottom. Lamina pinnately veined (or parallel-pinnate), or palmately veined, or parallel-veined; Stomata present; paracytic, or tetracytic (rarely). Lamina with secretory cavities. Secretory cavities containing latex; Secretory cavities schizogenous. The mesophyll containing calcium oxalate crystals, or without calcium oxalate crystals. The mesophyll crystals druses (?), or solitary-prismatic (no raphides). Minor leaf veins without phloem transfer cells (4 genera). Vessels absent.
Fruit characters
Fruits, Achenes or rarely follicles, usually numerous, sometimes longitudinally costate, agregated in an infrutescence, seeds 1-several.The fruiting carpels not coalescing. The fruiting carpel dehiscent, or indehiscent; a follicle, or an achene. Seeds non-endospermic. Seeds with starch. Cotyledons 1. Embryo achlorophyllous (3/5); strongly curved (horseshoe-shaped). Testa without phytomelan; usually membranous, sometimes thinly leathery, then brown.
Latex
present
Uses
Sagittaria,Alisma,Echinodorus, are used as ornamental plants in pools and aquaria. The roots of Sagittaria latifolia are used as food by the ancient North American Indians
Chemical characters
Cyanogenic (?), or not cyanogenic. Alkaloids present, or absent (2 species investigated). Iridoids not detected. Proanthocyanidins present, or absent; when present, cyanidin. Flavonols present, or absent; when present, kaempferol and quercetin. Ellagic acid absent. C3 and CAM. C3 physiology recorded directly in Alisma, Sagittaria. CAM recorded directly in Sagittaria subulata (aquatic CAM only). Anatomy non-C4 type (Sagittaria).
Distribution maps
(online von http://www.mobot.org/MOBOT/research/APweb/ . Dort zitiert wie unter jedem Diagramm vermerkt):
Alismataceae
map: see den Hartog 1957; Hultèn 1961; Meusel et al. 1965; Haynes & Holm-Nielsen 1997; Fl. Austral. 39: 2011
