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.

Ctenium polystachyum

HABIT Perennial; caespitose. Butt sheaths persistent and investing base of culm; with compacted dead sheaths, or fibrous dead sheaths. Culms 80–120 cm long. Ligule an eciliate membrane. Leaf-blades 15–30 cm long; 2–5 mm wide. Leaf-blade surface puberulous. Leaf-blade apex filiform.

INFLORESCENCE Inflorescence composed of racemes.

Racemes 3–6; digitate; arcuate; unilateral; 8–16 cm long. Rhachis semiterete; scabrous on surface; glabrous on surface; pubescent on margins; terminating in a barren extension; extension subulate. Spikelet packing broadside to rhachis; crowded; regular; 2 -rowed.

Spikelets pectinate; solitary. Fertile spikelets sessile.

FERTILE SPIKELETS Spikelets comprising 2 basal sterile florets; 1 fertile florets; with diminished florets at the apex. Spikelets cuneate; laterally compressed; 10 mm long; breaking up at maturity; disarticulating below each fertile floret. Floret callus pilose.

GLUMES Glumes persistent; dissimilar; exceeding apex of florets; firmer than fertile lemma; gaping. Lower glume lanceolate; 3–3.5 mm long; 0.33 length of upper glume; hyaline; 1-keeled; 1 -veined. Lower glume primary vein scaberulous. Lower glume lateral veins absent. Lower glume apex setaceously attenuate. Upper glume lanceolate; 10 mm long; 3 length of adjacent fertile lemma; herbaceous; with hyaline margins; 1-keeled; 3 -veined. Upper glume primary vein tuberculate. Upper glume surface tuberculate; rough on veins. Upper glume apex setaceously attenuate; awned; 1 -awned. Upper glume awn dorsal and oblique; 3–5 mm long.

FLORETS Basal sterile florets dissimilar; barren; without significant palea; attached to and deciduous with the fertile. Lemma of lower sterile floret ovate; 2 mm long; membranous; 1-keeled; 3 -veined; ciliate on margins; fringed all along; acute; awned. Awn of lower sterile floret subapical; 8 mm long. Lemma of upper sterile floret elliptic; 2 mm long; membranous; villous on margins; fringed above; emarginate; awned. Awn of upper sterile floret terminal; straight; 6 mm long. Fertile lemma ovate; 3 mm long; membranous; keeled; 3 -veined. Lemma margins villous; hairy above. Lemma apex awned; 1 -awned. Principal lemma awn subapical; 7 mm long overall. Palea 2 -veined. Apical sterile florets 1–2 in number; elliptic; 2.5 mm long.

FRUIT Caryopsis with adherent pericarp.

DISTRIBUTION South America: Brazil and southern South America.

NOTES Cynodonteae. N Amer Fl 1993.

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