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.

Orcuttia

HABIT Annual. Culms erect (4), or geniculately ascending (4), or decumbent (1), or prostrate (1); 2–12.5–35 cm long. Lateral branches lacking (2/3), or sparse (1/3). Leaves without demarcation between sheath and blade. Ligule absent. Leaf-blades viscid; aromatic.

INFLORESCENCE Inflorescence composed of racemes.

Racemes single; bilateral; bearing few fertile spikelets (1), or many spikelets (4); bearing 6–20 fertile spikelets on each (1/1). Rhachis angular. Spikelet packing broadside to rhachis; crowded (2), or contiguous (1), or lax (1), or distant (2).

Spikelets solitary. Fertile spikelets sessile.

FERTILE SPIKELETS Spikelets comprising 5–9 fertile florets (4), or 10–15 fertile florets, or 16–20 fertile florets (4), or 21–25 fertile florets (3), or 26–40 fertile florets (1); with diminished florets at the apex. Spikelets ovate; laterally compressed; 4–10–15 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes definite.

GLUMES Glumes persistent; shorter than spikelet. Lower glume lanceolate; 1 length of upper glume; chartaceous; without keels; 5–9 -veined. Lower glume surface without pits. Lower glume apex dentate (4), or lobed (1); 2 -fid (3), or 3 -fid, or 4–5 -fid (3); setaceously attenuate (1/1). Upper glume lanceolate; 0.5–0.6875–1 length of adjacent fertile lemma; chartaceous; without keels; 5–9 -veined. Upper glume apex dentate (4), or lobed (1); 2 -fid (3), or 3 -fid, or 4–5 -fid (3); setaceously attenuate (1/1).

FLORETS Fertile lemma oblong; chartaceous; keeled; wingless; 15 -veined. Lemma lateral veins prominent. Lemma surface unwrinkled; without grooves. Lemma apex lobed; 5 -fid; incised 0.33–0.415–0.5 of lemma length; mucronate (3), or awned (2); 5 -awned (4/4). Lateral lemma awns subequal to principal (1/1). Palea 0.75–0.95–1 length of lemma; 2 -veined. Apical sterile florets resembling fertile though underdeveloped.

FLOWER Lodicules absent. Anthers 3. Stigmas 2; sparsely hairy.

FRUIT Caryopsis with adherent pericarp; ellipsoid (3/4), or oblong (1/4); laterally compressed (4/4); smooth (2/2). Embryo 0.75–0.85–1 length of caryopsis.

DISTRIBUTION North America.

Please cite this publication as detailed in How to Cite Version: 27th January 2014.