Family: Poaceae |
J.K Wipff Plants annual or perennial; rhizomatous, rhizomes slender, terminating in a reduced panicle of cleistogamous spikelets. Culms 30-100 cm, erect or decumbent. Sheaths open; auricles absent; ligules of hairs; blades flat. Inflorescences subterranean and aerial, only the subterranean inflorescences forming mature caryopses; subterranean panicles with 1-5 spikelets; aerial panicles terminal, simple, with elongate rachises bearing erect to ascending branches, usually with 15 or more spikelets. Spikelets glabrous, unawned, with 2 florets. Subterranean spikelets setting seed, with 1 glume; lower glumes absent; upper glumes and lower lemmas similar in size and texture, exceeded by the upper florets; upper florets turgid, ellipsoidal; upper lemmas mostly indurate, margins thin, flat, apices acuminate; upper paleas similar in texture to the lemmas; anthers 3; caryopses well-developed. Aerial spikelets not setting seed, sometimes forming immature caryopses, lanceoloid, dorsally compressed to terete; glumes unequal or the lower glumes absent; upper glumes and lower lemmas similar in size and texture; upper lemmas mostly indurate, margins thin, flat, apices acute;lower florets staminate or sterile; upper florets with pistils but fruit not developed. x = 9. Name from the Greek amphikarpos, doubly fruit-bearing, a reference to the two kinds of spikelets. SELECTED REFERENCE McNamara, J. and J.A. Quinn. 1965. Resource allocation and reproduction in populations of Amphicarpum purshii Gramineae). Amer. J. Bot. 64:17-23. |