GrassBase - The Online World Grass Flora

Descriptions

W.D. Clayton, M. Vorontsova, K.T. Harman & H. Williamson

© Copyright The Board of Trustees, Royal Botanic Gardens, Kew.

Sorghastrum incompletum

HABIT Annual. Culms decumbent; weak; 30–300 cm long; without nodal roots, or rooting from lower nodes. Ligule an eciliate membrane. Leaf-blades 10–60 cm long; 3–10 mm wide.

INFLORESCENCE Inflorescence a panicle with branches tipped by a raceme.

Panicle open; lanceolate; 10–40 cm long. Panicle branches capillary.

Racemes bearing a triad of spikelets; 1 fertile spikelets on each. Rhachis obsolete.

Spikelets in threes. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 2 in the cluster. Pedicels filiform; ciliate.

STERILE SPIKELETS Companion sterile spikelets represented by barren pedicels.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets ovate; dorsally compressed; 4–5.5 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus pilose; base obtuse. Spikelet callus hairs white; 0.5–1.5 mm long.

GLUMES Glumes dissimilar; firmer than fertile lemma; shiny. Lower glume ovate; 1 length of spikelet; coriaceous; dark brown; without keels; 9 -veined. Lower glume surface pilose. Lower glume hairs white, or grey, or yellow. Lower glume apex truncate. Upper glume oblong; without keels.

FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret oblong; 1 length of spikelet; hyaline; 2 -veined; ciliate on margins. Fertile lemma oblong; hyaline; without keel. Lemma margins ciliolate. Lemma apex dentate; 2 -fid; awned; 1 -awned. Principal lemma awn from a sinus; bigeniculate; 25–40 mm long overall; with twisted column. Column of lemma awn pubescent; hairy on the spiral. Palea absent or minute.

FLOWER Lodicules 2; glabrous.

DISTRIBUTION Africa: west tropical, west-central tropical, northeast tropical, east tropical, southern tropical, and western Indian ocean. North America: Mexico. South America: Mesoamericana, northern South America, western South America, and Brazil.

NOTES Andropogoneae. FTEA.

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