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.

Orinus thoroldii

HABIT Perennial. Cataphylls evident. Rhizomes elongated. Culms erect; 30–50 cm long. Ligule an eciliate membrane; 1 mm long; lacerate. Leaf-blades flat, or involute; 10–15 cm long; 2–4 mm wide; glaucous. Leaf-blade surface ribbed; hirsute. Leaf-blade apex attenuate; hardened.

INFLORESCENCE Inflorescence composed of racemes.

Racemes 4–8; borne along a central axis; deflexed to erect; unilateral; 1–7 cm long. Central inflorescence axis 7–15 cm long. Rhachis angular. Spikelet packing broadside to rhachis.

Spikelets solitary. Fertile spikelets pedicelled. Pedicels oblong; 0.5–1 mm long; glabrous.

FERTILE SPIKELETS Spikelets comprising 2–3(–4) fertile florets; with diminished florets at the apex. Spikelets cuneate; laterally compressed; 7–9 mm long; breaking up at maturity; disarticulating below each fertile floret.

GLUMES Glumes persistent; similar; shorter than spikelet; thinner than fertile lemma. Lower glume lanceolate; 4–5 mm long; 0.8 length of upper glume; membranous; 1-keeled; 1 -veined. Lower glume primary vein scabrous. Lower glume lateral veins absent. Lower glume apex acute. Upper glume ovate; 5–6 mm long; 1 length of adjacent fertile lemma; membranous; without keels; 3 -veined. Upper glume surface scabrous; rough on veins. Upper glume margins eciliate, or ciliate. Upper glume apex acute.

FLORETS Fertile lemma elliptic; 5.5–6 mm long; chartaceous; mid-green to black; keeled; 3 -veined. Lemma surface pilose; hairy all along; hairy on back. Lemma apex acute; muticous, or mucronate. Palea lanceolate; 0.8 length of lemma; 2 -veined. Palea keels ciliate. Palea surface pilose. Apical sterile florets resembling fertile though underdeveloped.

FLOWER Lodicules 2; cuneate; fleshy. Anthers 3; 2.5–2.75 mm long.

FRUIT Caryopsis with adherent pericarp; fusiform; isodiametric; biconvex; 2.5 mm long. Embryo 0.33 length of caryopsis. Hilum elliptic.

DISTRIBUTION Asia-temperate: China. Asia-tropical: India.

NOTES Eragrostideae. Bor.

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