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.

Arthraxon

HABIT Annual (20), or perennial (3). Rhizomes absent (22), or short (1). Stolons absent (22), or present (1). Culms erect (2/22), or geniculately ascending (4/22), or decumbent (7/22), or rambling (13/22); slender (6/8), or weak (2/8); 5–41.5–200 cm long; firm (22), or wiry (1); rooting from lower nodes (9/9). Lateral branches lacking (1/5), or sparse (2/5), or ample (3/5). Ligule an eciliate membrane (3), or a ciliolate membrane (17), or a ciliate membrane (2), or a fringe of hairs (1). Leaf-blades lanceolate (22), or ovate (15); firm (17), or flaccid (6).

INFLORESCENCE Inflorescence composed of racemes.

Racemes single (4), or paired (10), or digitate (20), or borne along a central axis (1). Rhachis fragile at the nodes; angular (1/1). Rhachis internodes filiform (13), or linear (12).

Spikelets solitary (2), or in pairs (21). Fertile spikelets sessile; 1 in the cluster (21/21). Companion sterile spikelets pedicelled (21/21); 1 in the cluster (21/21). Pedicels filiform (12/22), or linear (9/22), or reduced to a stump (1/22).

STERILE SPIKELETS Companion sterile spikelets absent (2), or represented by barren pedicels (11), or represented by single glumes (2), or well-developed (9).

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets linear (2), or lanceolate (20), or elliptic (2), or ovate (1); laterally compressed (20), or subterete (1), or dorsally compressed (2); 0.8–5.191–10 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus brief (22), or square (1); glabrous (7/16), or pubescent (9/16), or pilose (1/16), or bearded (1/16); base truncate (19/21), or obtuse (2/21); attached transversely.

GLUMES Glumes exceeding apex of florets; firmer than fertile lemma. Lower glume lanceolate (22), or elliptic (1), or ovate (1); chartaceous (20), or coriaceous (3); without keels (17), or 2-keeled (6); 2–4 -veined (1/17), or 5 -veined (4/17), or 6 -veined (3/17), or 7 -veined (11/17), or 8 -veined (3/17), or 9 -veined (6/17), or 10–11 -veined (1/17). Lower glume lateral veins obscure (2), or distinct (21); intercarinal veins distinct (1/1). Lower glume surface convex (22), or flat (1); smooth (5), or asperulous (2), or scabrous (10), or spinose (7), or muricate (2); without pits; glabrous (21), or pubescent (1), or pilose (1), or villous (1). Lower glume apex entire (22), or dentate (1); 2 -fid (1/1); obtuse (1/10), or acute (7/10), or acuminate (1/10), or attenuate (1/10). Upper glume lanceolate; membranous (3), or chartaceous (20); with undifferentiated margins (22), or hyaline margins (1); 1-keeled; 3 -veined (15/16), or 4–5 -veined (2/16), or 7 -veined (1/16). Upper glume primary vein eciliate (21), or ciliolate (1), or ciliate (1). Upper glume surface smooth (20), or scabrous (3); glabrous (21), or pilose (2). Upper glume apex obtuse (1/22), or acute (21/22), or setaceously attenuate (1/22); muticous (22), or awned (1); 1 -awned (1/1).

FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret lanceolate (6), or oblong (17); hyaline; 0 -veined (10/18), or 2 -veined (8/18), or 3 -veined (1/18); obtuse (10/10). Fertile lemma linear (1), or lanceolate (17), or oblong (4), or ovate (1); hyaline; without keel; wingless; 0 -veined (1/22), or 1 -veined (20/22), or 2 -veined (1/22). Lemma surface unwrinkled; without grooves. Lemma apex entire (16), or dentate (3), or lobed (5); 2 -fid (8/8); acute (18/18); muticous (2), or awned (22); 1 -awned (22/22). Principal lemma awn dorsal (22/22); geniculate (22/22). Palea present (2), or absent or minute (21). Palea surface glabrous (1/2), or pubescent (1/2).

FLOWER Anthers 2–3 (12).

FRUIT Caryopsis with adherent pericarp (18/18); linear (2/5), or fusiform (1/5), or ellipsoid (1/5), or oblong (2/5); isodiametric (1/1).

DISTRIBUTION Africa (6), or Temperate Asia (14), or Tropical Asia (19), or Australasia (2), or Pacific (1), or North America (1), or South America (1).

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