Sorghastrum crassum

HABIT Perennial. Rootstock evident. Rhizomes short. Culms erect; 75–120 cm long; 2–3 mm diam. Culm-internodes terete. Leaves basal and cauline. Leaf-sheaths open for most of their length; striately veined; glabrous on surface, or puberulous (sparsely). Ligule an eciliate membrane; 2–3 mm long; membranous; lacerate (somewhat); obtuse. Leaf-blade base cordate; symmetrical. Leaf-blades tapering towards tip; flat; 25–40 cm long; 5–10 mm wide; coriaceous; stiff. Leaf-blade venation distinct. Leaf-blade surface glabrous. Leaf-blade apex acuminate.

INFLORESCENCE Inflorescence a panicle with branches tipped by a raceme.

Panicle contracted; linear, or lanceolate; 10–25 cm long. Panicle axis smooth.

Racemes flexuous. Rhachis fragile at the nodes; pilose on surface. Rhachis hairs white; 8 mm long. Rhachis internodes filiform; 5–8 mm long. Rhachis internode tip discoid; oblique.

Spikelets ascending; in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels filiform; 6–8 mm long; pubescent; hairy on surface; with white hairs (spreading); with 8 mm long hairs.

STERILE SPIKELETS Companion sterile spikelets represented by barren pedicels.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets lanceolate, or ovate (narrowly); dorsally compressed; 6.5–9 mm long; with hairs extending 3–5 mm beyond apex; falling entire; deciduous with accessory branch structures. Spikelet callus oblong; 1 mm long; pilose; base obtuse; attached obliquely.

GLUMES Glumes dissimilar; firmer than fertile lemma. Lower glume ovate (narrowly); 6.5–8 mm long; coriaceous; light brown (golden brown); without keels; 7–9 -veined. Lower glume lateral veins obscure. Lower glume surface asperulous; pilose; hairy below; with an apical beard. Lower glume apex dentate; 2 -fid. Upper glume narrowly ovate; 7.5–8 mm long; 1 length of spikelet; coriaceous; light brown (golden brown); without keels; 5 -veined. Upper glume primary vein obscure. Upper glume surface asperulous; glabrous. Upper glume apex acute.

FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret oblong; 5–6 mm long; hyaline; 2 -veined; minutely scaberulous; ciliate on margins (and apex); dentate (minutely); 2 -fid. Fertile lemma oblong (narrowly); 5–6 mm long; hyaline; without keel; 1 -veined. Lemma surface asperulous; pilose. Lemma apex awned; 1 -awned. Principal lemma awn straight; 20–25 mm long overall; limb scaberulous. Palea absent or minute.

FLOWER Anthers 3; oblong; 3.5 mm long. Stigmas 2.

DISTRIBUTION South America: western South America.

NOTES Andropogoneae. Renvoize 2007.

Please cite this publication as detailed in How to Cite Version: 3rd February 2016.