Arthraxon hispidus

Plants annual. Culms 0.5-1(2) m, weak, often decumbent and rooting at the lower nodes; nodes hispid. Leaves cauline; sheaths usually shorter than the internodes; ligules 0.4-3.5 mm, ciliate; lower blades 1-7.5 cm long, 4-20 mm wide, cordate-clasping, ovate to ovate-lanceolate, flat, margins ciliate (sometimes sparingly so), surfaces usually glabrous, abaxial surface rarely hispidulous; upper blades greatly reduced. Panicles 1.3-7 cm, flabellate or contracted, with 12-20 rames; rames 1-6(11) cm. Sessile spikelets: glumes 3-5.5 mm, lanceolate; lower glumes several-veined; upper glumes 1- or 3-veined; awns 0.3-9 mm, included or exserted, usually twisted below, sometimes geniculate at midlength; anthers usually 2, 0.5-0.7 mm. Pedicels absent or to 2 mm. Pedicellate spikelets absent. 2n = 36.

Arthraxon hispidus is native to Asia, but is naturalized and spreading along roadsides, shores, ditches and in low woods and fields of the eastern United States. It is also naturalized in Mexico, Central America, and the West Indies. Plants in the Flora region belong to A. hispidus (Thunb.) Makino var. hispidus, the most widespread and variable of the four varieties. Arthraxon castratus (Griff.) V. Naray. ex Bor, reported from Puerto Rico, differs from A. hispidus in having pilose lemma margins, a palea in its second floret, and three anthers.

Slender, lax, decumbent annual to 5(-10) dm; blades 2-7 cm נ5-15 mm; spikes few-several, digitate, 2-8 cm; normal spikelet (2-)3-5(-8) mm, the lower glume 4-15-veined and with the veins usually spiculate-scabrous at least distally, the upper inconspicuously 3- or 5-veined; sterile lemma virtually veinless, the fertile one 1-veined, often with a supra-basal awn to 10 mm; anthers usually 2; sterile spikelet reduced to the 1-4 mm pedicel, or obsolete; 2n=10. A weed of moist or wet soil, native to se. Asia, now widely intr. in warm regions, and found here and there in our range, n. as far as Mo. and s. N.Y.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

©The New York Botanical Garden. All rights reserved. Used by permission.

From Flora of Indiana (1940) by Charles C. Deam

 

Indiana Coefficient of Conservatism: C = null, non-native

Wetland Indicator Status: FACW