197. Najadaceae A. L. de Jussieu
Naiad Family, or Water-nymph Family
Robert R. Haynes
Herbs, annual, rarely perennial, not rhizomatous, caulescent; turions absent. Leaves nearly opposite or appearing whorled, submersed, sessile; sheath not persisting longer than blade, not leaving scar when shed, not ligulate, not auriculate or rarely auriculate; intravaginal squamules scales, 2, linear. Inflorescences axillary, solitary flowers or cymes, often subtended by spathe as involucre, sessile or short-pedunculate. Flowers unisexual, staminate and pistillate on same or separate plants; subtending bracts absent; perianth absent; stamens 1; anthers dehiscing irregularly; pollen spheric; pistils 1, not stipitate; ovules basal, anatropous. Fruits achenelike. Seeds 1; embryo straight.
Genus Genera 1, species 40 (8 species in the flora): nearly worldwide.
SELECTED REFERENCES
Haynes, R. R. 1977. The Najadaceae in the southeastern United States. J. Arnold Arbor. 58: 161--170. Shaffer-Fehre, M. 1991. The endotegmen tuberculae: An account of little-known structures from the seed coat of the Hydrocharitoideae (Hydrocharitaceae) and Najas (Najadaceae). Bot. J. Linn. Soc. 107: 169--188. Shaffer-Fehre, M. 1991b. The position of Najas within the subclass Alismatidae (Monocotyledones) in the light of new evidence from seed coat structures in the Hydrocharitoideae (Hydrocharitales). Bot. J. Linn. Soc. 107: 189--209. Thorne, R. F. 1993c. Hydrocharitaceae. In: J. C. Hickman, ed. 1993. The Jepson Manual: Higher Plants of California. Berkeley, Los Angeles, and London. Pp. 1150--1151.
