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.

Acroceras

HABIT Annual (7), or perennial (10). Rhizomes absent (16), or elongated (1). Stolons absent (16), or present (1). Culms erect (2), or decumbent (13), or prostrate (2), or rambling (4); weak (2/2); 5–52.5–200 cm long; rooting from lower nodes (14/14). Lateral branches sparse (2/3), or ample (1/3). Ligule an eciliate membrane (12), or a ciliolate membrane (5), or a fringe of hairs (1), or absent (1). Leaf-blades linear (7), or lanceolate (13), or oblong (1), or ovate (1); firm (16), or flaccid (1). Leaf-blade midrib evident (1/2), or conspicuous (1/2). Leaf-blade venation without cross veins (14), or with obscure cross veins (3), or with distinct cross veins (1). Leaf-blade margins cartilaginous (2/2).

INFLORESCENCE Inflorescence a panicle (3), or composed of racemes (13), or comprising only a few spikelets (1); terminal (16), or terminal and axillary (1).

Panicle open (2/2).

Racemes borne along a central axis (13/13); appressed (1/13), or ascending (12/13); unilateral (13/13). Rhachis wingless (12/13), or narrowly winged (1/13); angular (9/9). Spikelet packing contiguous (6/13), or lax (5/13), or distant (2/13).

Spikelets appressed (1/7), or ascending (6/7); solitary (7), or in pairs (15). Fertile spikelets sessile (1), or sessile and pedicelled (2), or pedicelled (14); 1 in the cluster (3/11), or 2 in the cluster (11/11). Pedicels free (15/16), or fused to each other (1/16); filiform (1/12), or linear (11/12).

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets lanceolate (2), or elliptic (9), or oblong (2), or ovate (3), or obovate (1); laterally compressed (12), or subterete (4), or dorsally compressed (1); 1.5–3.612–6.5 mm long; falling entire. Spikelet callus brief (15), or square (2); glabrous (10/10); base truncate (11/11). Rhachilla internodes brief up to lowest fertile floret (12), or elongated between glumes (5).

GLUMES Glumes shorter than spikelet (9), or reaching apex of florets (8); thinner than fertile lemma. Lower glume lanceolate (1), or elliptic (1), or ovate (15); clasping (5/5); membranous (2), or herbaceous (15); without keels (16), or 1-keeled (1); 3 -veined (13), or 4 -veined (2), or 5 -veined (6), or 6–7 -veined (2). Lower glume surface smooth (16), or asperulous (1), or rugose (1); without pits; glabrous (13), or puberulous (3), or pubescent (1), or pilose (1). Lower glume apex obtuse (3), or acute (10), or acuminate (1), or cuspidate (2), or laterally pinched (1); muticous (15), or mucronate (2), or awned (1). Upper glume lanceolate (2), or elliptic (7), or ovate (9); membranous (2), or herbaceous (15); without keels (5/6), or 1-keeled (1/6); 3 -veined (1), or 5 -veined (13), or 7 -veined (2), or 9–11 -veined (1). Upper glume surface smooth (14), or asperulous (1), or rugose (2); glabrous (10), or puberulous (5), or pubescent (1), or pilose (1). Upper glume apex obtuse (3/16), or acute (3/16), or acuminate (1/16), or laterally pinched (9/16); muticous (15), or mucronate (2).

FLORETS Basal sterile florets male (10), or barren (9); with palea (14), or without significant palea (3). Lemma of lower sterile floret lanceolate (2), or elliptic (3), or oblong (3), or ovate (9); 1 length of fertile lemma; membranous (2), or herbaceous (15); 3 -veined (1/13), or 5 -veined (10/13), or 7 -veined (1/13), or 11 -veined (1/13); obtuse (4), or acute (5), or laterally pinched at apex (8); muticous (15), or mucronate (2). Palea of lower sterile floret hyaline (13/14), or membranous (1/14). Fertile lemma lanceolate (1), or elliptic (10), or oblong (1), or ovate (4), or oblanceolate (1); dorsally compressed; lanceolate in profile (1/1); coriaceous (1), or indurate (16); wingless; 3 -veined (1/2), or 5 -veined (1/2). Lemma surface smooth (14), or papillose (1), or striate (2); unwrinkled; without grooves. Lemma margins involute. Lemma apex obtuse (2), or acute (11), or apiculate (4); without ornament (4), or laterally pinched (2), or with a little green crest (11), or with a green spot (2), or with a shallow excavation (2), or pubescent (5); muticous (13), or mucronate (4). Palea embraced by lemma (7), or reflexed at apex (10); not rolled (1), or involute (16); 1 length of lemma; coriaceous (1), or indurate (16); 2 -veined (11/11); without keels (5), or 2-keeled (12). Palea apex lobed (1/1).

FLOWER Lodicules 2 (3/3); fleshy (1/1); irregularly toothed (1/1). Anthers 2 (1/5), or 3 (4/5). Stigmas 2 (1/1).

FRUIT Caryopsis with adherent pericarp (4/4); ellipsoid (1/2), or oblong (1/2); dorsally compressed (1/1); plano-convex (1/1). Embryo 0.4–0.475–0.5 length of caryopsis. Hilum punctiform (2/3), or linear (1/3); 1 length of caryopsis.

DISTRIBUTION Africa (11), or Temperate Asia (3), or Tropical Asia (3), or North America (1), or South America (5).

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