GrassBase - The Online World Grass Flora


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

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

Ischaemum arenosum

HABIT Perennial. Culms decumbent; 20–60 cm long; rooting from lower nodes. Culm-nodes glabrous, or pubescent. Leaf-sheaths longer than adjacent culm internode; glabrous on surface. Ligule an eciliate membrane; 1.5 mm long. Leaf-blades 2–10 cm long; 3–7 mm wide. Leaf-blade venation prominent. Leaf-blade surface glabrous; hairless except near base.

INFLORESCENCE Inflorescence composed of racemes.

Racemes 1; single; 5 cm long. Rhachis fragile at the nodes; angular; ciliate on margins. Rhachis internodes oblong; 4.5 mm long. Rhachis internode tip transverse; cupuliform.

Spikelets in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels oblong; ciliate.

STERILE SPIKELETS Companion sterile spikelets well-developed; male; elliptic; laterally compressed; 3.5–4.5 mm long; as long as fertile; separately deciduous. Companion sterile spikelet glumes chartaceous; keeled; 9 -veined; pilose. Companion sterile spikelet lemmas 2; enclosed by glumes; 2.5–3 mm long; 1-awned; with 4–5.5 mm long awn.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets elliptic; dorsally compressed; 3.8–4.8 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus pubescent; base truncate; inserted.

GLUMES Glumes dissimilar; exceeding apex of florets; firmer than fertile lemma. Lower glume elliptic; 3.5–4.5 mm long; 1 length of spikelet; coriaceous; 2-keeled; keeled all along; keeled laterally; wingless; 9 -veined. Lower glume surface convex; pilose. Lower glume margins ciliate. Lower glume apex emarginate. Upper glume elliptic; 1 length of spikelet; coriaceous; 1-keeled; 3(–5) -veined. Upper glume surface pilose; hairy above. Upper glume muticous.

FLORETS Basal sterile florets male; with palea. Lemma of lower sterile floret elliptic; 3.5 mm long; hyaline; 3(–5) -veined; acuminate. Palea of lower sterile floret 1 length of lemma. Fertile lemma lanceolate; 3–3.4 mm long; hyaline; without keel; 3(–5) -veined. Lemma apex lobed; 2 -fid; awned; 1 -awned. Principal lemma awn from a sinus; geniculate; 3.5–6 mm long overall; with twisted column. Column of lemma awn glabrous. Palea 1 length of lemma.

FLOWER Lodicules 2; adnate to palea; 0.4–0.5 mm long. Anthers 3; 0.8–1 mm long.

DISTRIBUTION South America: northern South America.

NOTES Andropogoneae. Sohns 2004.

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