Alismataceae

Herbs, annual or perennial, rhizomatous, stoloniferous, or cormose, caulescent, glabrous to stellate-pubescent; sap milky. Roots septate or not septate. Leaves basal, submersed, floating, or emersed, sessile or petiolate, sheathing proximally; blade with translucent markings of dots or lines present or absent, basal lobes present or absent; venation reticulate, primary veins parallel from base of blade to apex, secondary veins reticulate. Inflorescences scapose racemes or panicles, rarely umbels, erect, rarely floating or decumbent, whorled (forming racemes) or whorls branching (forming panicles), bracteolate. Flowers bisexual or unisexual, if unisexual, staminate and pistillate on same or different plants, hypogynous, subsessile to long-pedicellate; sepals persistent, 3; petals deciduous, 3, delicate; stamens 0, 6, 9, or to 30, distinct; anthers 2-loculed, dehiscing longitudinally; pistils 0 or 6–1500 or more, distinct or coherent proximally, 1-loculed; placentation basal; ovules1–2. Fruits achenes or follicles. Seeds: embryo U-shaped; endosperm absent in mature seed.

Distribution

Nearly worldwide, primarily tropical and subtropical regions.

Discussion

Genera 12, species ca. 80 (4 genera, 34 species in the flora).

Selected References

Argue, C. L. 1974. Pollen studies in the Alismataceae (Alismaceae). Bot. Gaz. 135: 338--344.

Argue, C. L. 1976. Pollen studies in the Alismataceae with special reference to taxonomy. Pollen & Spores 18: 161--173.

Beal, E. O. 1960b. The Alismataceae of the Carolinas. J. Elisha Mitchell Sci. Soc. 76: 68--79.

Charlton, W. A. 1973. Studies in the Alismataceae. II. Inflorescences of Alismataceae. Canad. J. Bot. 51: 775--789.

Correll, D. S. and H. B. Correll. 1972. Aquatic and Wetland Plants of Southwestern United States. Washington.

Godfrey, R. K. and J. W. Wooten. 1979. Aquatic and Wetland Plants of Southeastern United States: Monocotyledons. Athens, Ga.

Haynes, R. R. and L. B. Holm-Nielsen. 1985. A generic treatment of Alismatidae in the Neotropics. Acta Amazôn. 15(suppl.): 153--193.

Haynes, R. R. and L. B. Holm-Nielsen. 1994. The Alismataceae. In: Organization for Flora Neotropica. 1968+. Flora Neotropica. 75+ nos. New York. No. 64, pp. 1--112.

Rogers, G. K. 1983. The genera of Alismataceae in the southeastern United States. J. Arnold Arbor. 64: 387--424.

Lower Taxa

Alisma, Damasonium, Echinodorus, Sagittaria

Illustrations

	Family ⠉	Taxon	Illustrator ⠉
	Alismataceae Alismataceae Alismataceae	Sagittaria montevidensis Echinodorus cordifolius subsp. cordifolius Damasonium californicum	John Myers John Myers John Myers
	Alismataceae Alismataceae Alismataceae	Sagittaria isoetiformis Sagittaria papillosa Sagittaria platyphylla	John Myers John Myers John Myers
	Alismataceae Alismataceae Alismataceae	Sagittaria rigida Sagittaria brevirostra Sagittaria cuneata	John Myers John Myers John Myers
... further results

Key

1	Pistils weakly coherent proximally into starlike aggregation; petals erose	Damasonium
1	Pistils distinct, forming heads or rings; petals entire.	> 2
2	Pistils arranged in ring around margin of flattened receptacle.	Alisma
2	Pistils spirally arranged on convex receptacle.	> 3
3	Flowers all bisexual; fruits mostly plump, longitudinally ribbed, lateral wings absent.	Echinodorus
3	Flowers unisexual (at least the proximal); fruits compressed, lateral wing often present, 1, curved.	Sagittaria