Urochloa panicoides Beauv.

(=Panicum helopus Trin.)

Family: Poaceae,  Tribe: Paniceae

Common names:  liverseed grass

Disseminule:  Spikelet; disarticulation below glumes.

Description

Spikelets of 1 fertile floret and 1 basal sterile lemma; spikelet elliptic, strongly dorsally compressed, plano-convex, apex acute; 2.5-5.5 mm long, 1.8-2.25 mm wide. Glumes membranous, dissimilar; lower glume ca. one third as long as spikelet, 3-5-nerved, upper glume as long as spikelet, 7-13-nerved. Sterile lemma similar to upper glume, but 5-7-nerved. Fertile lemma elliptic, indurate, surface with numerous, low transverse ridges, apex obtuse and awned, awn 0.3-1 mm long, not extending beyond tip of spikelet; lemma margins inrolled, enclosing palea.

Identification remarks

Similar species

Urochloa ramosa (L.) R.D. Webster

Urochloa texana (Buckley) R.D. Webster

Distribution

Africa: Botswana, Eritrea, Ethiopia, Kenya, Malawi, Mauritius, Mozambique, Namibia, Somalia, South Africa, Sudan, Swaziland, Tanzania, Uganda, Zambia, Zimbabwe; Asia: Yemen, India, Pakistan, Thailand; Australia; Argentina; United States.

Native to southern Africa.

Habitat

Woodlands, shrublands, damp places; a weed of lawns, roadsides, rotation crops, pastures.

General information

Urochloa panicoides is a tufted annual grass, to 100 cm tall. In Australia, it grows in tropical-subtropical sub-humid woodlands to semi-arid shrub woodlands. It is reported to cause nitrate poisoning in livestock.

A, Spikelet in ventral view showing lower glume and sterile lemma; B, spikelet in dorsal view showing upper glume; C, floret in ventral view showing palea and margins of fertile lemma; D, floret in dorsal view showing lemma

Caryopsis in ventral view

photo by Mark Thurmond

Portions of inflorescence

photo by Mark Thurmond

A, Spikelet in ventral view; B, spikelet in dorsal view; C, floret in ventral view; D, floret in dorsal view; E, caryopsis in ventral view; F, caryopsis in dorsal view

drawing by Lynda E. Chandler

A, spikelet in dorsal view showing upper glume; B, Spikelet in ventral view showing lower glume and sterile lemma; C, floret in dorsal view showing lemma; D, floret in ventral view showing palea and margins of fertile lemma

Spikelets; in ventral view showing lower glume and sterile lemma (left) and dorsal view showing upper glume (right)

A-B, Florets in dorsal and ventral view; C, caryopsis in ventral view; D, caryopsis in dorsal view