Disakisperma Steud., Syn. Pl. Glumac. 1: 287. 1854.

Snow, Neil, Peterson, Paul M. & Romaschenko, Konstantin, 2013, Systematics of Disakisperma (Poaceae, Chloridoideae, Chlorideae), PhytoKeys 26, pp. 21-70 : 25

Disakisperma Steud., Syn. Pl. Glumac. 1: 287. 1854.

Type species.

Disakisperma mexicana Steud. = Disakisperma dubium (Kunth) P.M. Peterson & N. Snow.

Description.

Plants perennial, rarely annual in a few populations, occasionally stoloniferous. Culms 30-200 cm long, solid, decumbent or clambering to erect; nodes glabrous. Leaf sheaths half as long to slightly longer than internodes, glabrous or ciliate apically along margins; ligule membranous, 0.5-1.5 mm long, ciliate or fimbriate apically; leaf blades cauline, linear. Inflorescence apical and exserted at maturity or cleistogamous in lower leaf sheaths, a panicle composed of several to numerous unilateral racemes, racemosely or subdigitately scattered along a central axis; branches at maturity slightly reflexed to ascending or steeply erect. Spikelets sessile to subsessile, dorsally rounded to flattened, typically overlapping, disarticulation above the glumes; florets 4-13; glumes 2, 1-nerved or occasionally with remnants of two additional nerves near base, mucronate or emucronate; lemmas 3-nerved, rarely with remnants of two additional nerves near base, sometimes cartilaginous towards the base, macrohairs acute, obtuse, or clavicorniculate; paleas often somewhat cartilaginous towards base. Stamens 3. Lodicules 2, flabellate. Caryopses dorsally flattened, broadly concave on the hilar surface; pericarp weakly adnate to endosperm. 2 n = 40, 60, 80 ( Snow 1997).

Vernacular name.

In light of its only recent resurrection from generic synonymy ( Peterson et al. 2012), no common name exists for Disakisperma . We suggest Jacobsgrass to honor the memory of Dr. Surrey W. L. Jacobs (1946-2009), an Australian friend, colleague, and chloridoid specialist (e.g., Jacobs 1988).

Key to the species of Disakisperma

1	Panicles 1-3 cm wide; branches mostly erect or steeply ascending, stiff, 2-10.5 cm long	2
-	Panicles 3-25 cm wide; branches ascending but not steeply so, usually reflexed (towards tips) and somewhat flexuous, (-1.5) 3-19 cm long.	3
2	Lemmas membranous throughout, margins not involute near base; adaxial leaf blades surfaces without long hairs; anthers 0.9-1.0 mm long	Disakisperma eleusine
-	Lemmas cartilaginous below, margins involute near base; adaxial leaf blade with scattered, delicate, straight hairs near the base, the hairs 3-5 mm long; anthers 0.2-0.3 mm long	Disakisperma yemenicum
3	Lemmas 3.5-5.0 mm long with round- to acute-tiped hairs along margins and sometimes the midnerve below; glumes 3.3-6.0 mm long; cleistogamous spikelets hidden in lower leaf sheaths; anthers 1.0-1.6 mm long; native to the Americas	Disakisperma dubium
-	Lemmas 2.2-2.8 (-3.0) mm long with clavicorniculate (club-shaped) hairs along the margins and midnerve below; glumes 1.5-2.9 mm long; cleistogamous spikelets absent in the lower leaf sheaths; anthers about 0.7 mm long; native to Africa and Asia	Disakisperma obtusiflorum