Echinochloa oplismenoides

(E. Fourn.) Hitchc.
Common names: Chihuahuan barnyard grass
Treatment appears in FNA Volume 25. Treatment on page 398.

Plants annual. Culms to 100 cm, erect, succulent, glabrous, branching from the lower nodes. Sheaths glabrous or hispid with papillose-based hairs; ligules absent or the ligule region pubescent; blades 10-35 cm long, 5-10 mm wide. Panicles 15-30 cm, narrow; primary branches appressed to ascending, with papillose-based hairs at the base of the spikelets. Spikelets 4-5 mm, disarticulating at maturity. Glumes with hairs over the veins, glabrous, scabrous, or hispid between the veins; upper glumes about equal to the spikelets, muticous or awned, awns to 1 mm; lower florets sterile; lower lemmas unawned or awned, awns 8-16(50) mm; lower paleas absent or hyaline and subequal to the lemmas; upper lemmas 4-4.5 mm long, 1.7-1.9 mm wide, elliptic; anthers 0.5-0.7 mm, purple. Caryopses 2.7-2.9 mm long, 1.7-1.8 mm wide, elliptic in outline, mucronate; embryos about 75% as long as the caryopses; hila obovate. 2n = unknown.


Echinochloa oplismenoides was first found in the United States, in southern Arizona, in 1993 (Fishbein 1995). It was previously known only from Mexico, with a range that extends from northwestern Mexico to Guatemala. The southern Arizonan plants were found near a cattle tank in wet grasslands. Fishbein stated that it was impossible to tell whether they represented a previously overlooked native species or an introduction.

Selected References


Lower Taxa