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Descriptions
W.D. Clayton, M. Vorontsova, K.T. Harman & H. Williamson
© Copyright The Board of Trustees, Royal Botanic Gardens, Kew.
Ischaemum amethystinum
HABIT Perennial; caespitose. Butt sheaths woolly. Culms 150–300 cm long. Culm-nodes bearded. Ligule an eciliate membrane. Leaf-blades 30–60 cm long; 3–15 mm wide.
INFLORESCENCE Inflorescence composed of racemes.
Racemes (1–)3–4(–6); digitate; 12–22 cm long. Rhachis fragile at the nodes; subterete; villous on margins. Rhachis internodes cuneate. Rhachis internode tip transverse; cupuliform.
Spikelets in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels narrowly elliptic; terete; villous.
STERILE SPIKELETS Companion sterile spikelets well-developed; containing empty lemmas, or male; lanceolate; 8–10 mm long; as long as fertile; separately deciduous. Companion sterile spikelet glumes chartaceous; muticous. Companion sterile spikelet lemmas 2; enclosed by glumes; muticous.
FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets lanceolate, or elliptic; dorsally compressed; 7–11 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus base obtuse; inserted.
GLUMES Glumes dissimilar; exceeding apex of florets; firmer than fertile lemma. Lower glume elliptic; 1 length of spikelet; coriaceous; 2-keeled; keeled above; keeled laterally; winged on keel; winged narrowly; winged near apex. Lower glume surface convex; villous. Lower glume hairs purple. Lower glume apex dentate; 3 -fid. Upper glume lanceolate; chartaceous; 1-keeled.
FLORETS Basal sterile florets male; with palea. Lemma of lower sterile floret lanceolate; 1 length of spikelet; membranous. Fertile lemma oblong; membranous; without keel. Lemma apex lobed; 2 -fid; awned; 1 -awned. Principal lemma awn from a sinus; geniculate; 20–45 mm long overall; with twisted column. Column of lemma awn glabrous. Palea 1 length of lemma.
DISTRIBUTION Africa: west tropical, west-central tropical, northeast tropical, and east tropical.
NOTES Andropogoneae. FTEA.
Please cite this publication as detailed in How to Cite Version: 3rd February 2016.