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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.
Ischaemum decumbens
HABIT Annual. Culms rambling; 5–30 cm long. Culm-nodes bearded. Leaf-sheaths glabrous on surface. Ligule a ciliolate membrane; 1–1.5 mm long. Leaf-blades linear, or lanceolate; 2–5 cm long; 3–5 mm wide. Leaf-blade surface pilose; sparsely hairy.
INFLORESCENCE Inflorescence composed of racemes.
Racemes 2; paired; appressed back to back; 2–4 cm long. Rhachis fragile at the nodes; angular; ciliate on margins. Rhachis internodes clavate; 2 mm long; flat and forming a U or V shape with the pedicel in rear view. Rhachis internode tip transverse; cupuliform.
Spikelets in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels clavate; 0.5 mm long; 0.25 length of internode; ciliate.
STERILE SPIKELETS Companion sterile spikelets well-developed; comprising 2 subequal glumes without lemmas; lanceolate; laterally compressed; 2–6 mm long; shorter than fertile; separately deciduous. Companion sterile spikelet glumes chartaceous; keeled; awned; one glume awned.
FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets oblong; dorsally compressed; 5–6 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus base truncate; inserted.
GLUMES Glumes dissimilar; exceeding apex of florets; firmer than fertile lemma; shiny. Lower glume ovate; 1 length of spikelet; coriaceous; 2-keeled; keeled above; keeled laterally; wingless. Lower glume surface convex. Lower glume apex dentate; 2 -fid; acuminate; awned; 1–2 -awned. Lower glume awn 0.5 mm long. Upper glume lanceolate; coriaceous; 1-keeled. Upper glume awned; 1 -awned. Upper glume awn 2–6 mm long.
FLORETS Basal sterile florets male; with palea. Lemma of lower sterile floret lanceolate; membranous; 3 -veined. Fertile lemma oblong; membranous; without keel. Lemma apex lobed; 2 -fid; awned; 1 -awned. Principal lemma awn from a sinus; geniculate; 12–14 mm long overall; with twisted column. Column of lemma awn glabrous.
FLOWER Anthers 3.
DISTRIBUTION Australasia: Australia.
NOTES Andropogoneae. WDC 1993.
Please cite this publication as detailed in How to Cite Version: 3rd February 2016.
