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.

Acrachne

HABIT Annual. Culms geniculately ascending, or decumbent; 10–31.66–75 cm long; rooting from lower nodes (1/1). Lateral branches sparse (1/1). Ligule an eciliate membrane (1), or a ciliolate membrane (2). Leaf-blades firm (2), or flaccid (1). Leaf-blade margins unthickened (1), or cartilaginous (2).

INFLORESCENCE Inflorescence composed of racemes.

Racemes digitate (2), or borne along a central axis; unilateral. Rhachis flattened (1), or angular (2); terminating in a sterile spikelet, or barren extension (1); extension subulate (1/1). Spikelet packing broadside to rhachis; 1 -rowed (1), or 2 -rowed (2).

Spikelets appressed (2/2); solitary, or in pairs (1). Fertile spikelets sessile; 1–2 in the cluster (1/1).

FERTILE SPIKELETS Spikelets comprising 2 fertile florets (1), or 3–5 fertile florets (2), or 6 fertile florets, or 7–25 fertile florets (1); with diminished florets at the apex. Spikelets oblong; laterally compressed; 2–5.416–13 mm long; breaking up at maturity; rhachilla persistent; retaining paleas. Rhachilla internodes definite.

GLUMES Glumes deciduous; shorter than spikelet; parallel to lemmas (2), or recurved at apex (1). Lower glume lanceolate (2), or ovate (1); 0.5–0.8–1 length of upper glume; membranous; 1-keeled; 1 -veined. Lower glume lateral veins absent. Lower glume surface without pits. Lower glume apex acute (1), or acuminate (2); muticous (1), or mucronate (2). Upper glume oblong (1), or ovate (2); 0.5–0.8333–1 length of adjacent fertile lemma; membranous; 1-keeled; 1 -veined. Upper glume apex acuminate (2), or setaceously attenuate (1); muticous (1), or mucronate (1), or awned (1); 1 -awned (1/1).

FLORETS Fertile lemma oblong (1), or ovate (2); laterally compressed; oblong in profile (1), or ovate in profile (2); membranous; keeled; wingless; 3 -veined. Lemma midvein scaberulous. Lemma lateral veins excurrent (1), or extending close to apex (1), or stopping well short of apex (1). Lemma surface unwrinkled; without grooves. Lemma apex acute (2), or acuminate (1); awned; 1 -awned. Palea 0.8 length of lemma; 2 -veined. Palea keels scabrous. Palea apex dentate (1/1). Apical sterile florets resembling fertile though underdeveloped.

FLOWER Lodicules 2; fleshy. Anthers 3. Stigmas 2.

FRUIT Caryopsis with free soft pericarp; ellipsoid; isodiametric (2), or laterally compressed (1); biconvex (2/2); smooth (1), or granular (1), or rugose (2); apex unappendaged. Embryo 0.3–0.3767–0.5 length of caryopsis. Hilum punctiform.

DISTRIBUTION Africa (2), or Temperate Asia (1), or Tropical Asia (2), or Australasia (1), or South America (1).

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