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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 brunneum
HABIT Perennial; caespitose. Culms erect; 50–160 cm long; 1–3 mm diam. Leaf-sheaths 14–30 cm long; glabrous on surface; outer margin glabrous, or hairy. Ligule a ciliolate membrane; 2–4 mm long. Leaf-blades flat, or conduplicate; 15–35 cm long; 2–6 mm wide. Leaf-blade surface scabrous; rough on both sides; glabrous, or pubescent; hairy adaxially. Leaf-blade margins scabrous.
INFLORESCENCE Inflorescence a panicle with branches tipped by a raceme. Peduncle 15–35 cm long.
Panicle open; linear; equilateral, or nodding; 10–35 cm long. Panicle axis smooth, or scabrous; glabrous.
Racemes bearing a triad of spikelets, or few fertile spikelets; 1–2 fertile spikelets on each. Rhachis fragile at the nodes. Rhachis internodes filiform.
Spikelets in pairs, or in threes. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster, or 2 in the cluster. Pedicels filiform; 3.5 mm long; pubescent.
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; dorsally compressed; 5–6.5 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus pubescent; base obtuse.
GLUMES Glumes dissimilar; firmer than fertile lemma. Lower glume oblong; 1 length of spikelet; coriaceous; dark brown; without keels; 7–9 -veined. Lower glume surface pubescent. Lower glume apex truncate. Upper glume oblong; 1 length of spikelet; coriaceous; without keels; 5 -veined. Upper glume surface glabrous. Upper glume apex acute.
FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret oblong; 3–5 mm long; hyaline; 2 -veined; ciliate on margins; dentate; 2 -fid. Fertile lemma oblong; 2–5 mm long; hyaline; without keel; 3 -veined. Lemma margins ciliolate. Lemma apex lobed; 2 -fid; awned; 1 -awned. Principal lemma awn from a sinus; bigeniculate; 15–25 mm long overall; with twisted column. Column of lemma awn hispidulous. Palea absent or minute.
FLOWER Lodicules 2; glabrous. Anthers 3; 2–3.5 mm long.
FRUIT Caryopsis 2–2.5 mm long.
DISTRIBUTION North America: Mexico. South America: Mesoamericana.
NOTES Andropogoneae. Davila 1993.
Please cite this publication as detailed in How to Cite Version: 3rd February 2016.
