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.

Sorghastrum

HABIT Annual (2), or perennial (18). Rhizomes absent (14), or short (3), or elongated (3). Culms erect (14/16), or geniculately ascending (1/16), or decumbent (1/16), or rambling (1/16), or scandent (1/16); slender (1/2), or weak (1/2); 30–130.9–300 cm long; without nodal roots (1/3), or with prop roots (1/3), or rooting from lower nodes (2/3). Culm-internodes terete (1/1). Culm-nodes constricted (1/1). Lateral branches lacking (2/2). Leaf-sheaths open for most of their length (1/1). Leaf-sheath auricles absent (18), or erect (2). Ligule an eciliate membrane (17), or a ciliolate membrane (2), or a fringe of hairs (1). Leaf-blades filiform (1), or linear (19); herbaceous (19), or coriaceous (1); stiff (2), or firm (18).

INFLORESCENCE Inflorescence a panicle with branches tipped by a raceme.

Panicle open (17), or contracted (3). Primary panicle branches not whorled (19), or whorled at lower nodes (1).

Racemes bearing a triad of spikelets (15), or few fertile spikelets (15), or many spikelets (2); 1 fertile spikelets on each (14/16), or 2 fertile spikelets on each (12/16), or 3 fertile spikelets on each (7/16), or 4–7 fertile spikelets on each (2/16), or 8–15 fertile spikelets on each (1/16). Rhachis evident (18), or obsolete (2); tough (2), or fragile at the nodes (18). Spikelet packing contiguous (17/18), or lax (1/18). Rhachis internodes indefinite (1/18), or filiform (17/18). Rhachis internode tip oblique (1/1).

Spikelets ascending (1/1); in pairs (17), or in threes (14). Fertile spikelets sessile, or sessile and pedicelled (2); 1 in the cluster, or 2 in the cluster (2). Companion sterile spikelets pedicelled; 0 in the cluster (2), or 1 in the cluster (17), or 2 in the cluster (14). Pedicels filiform.

STERILE SPIKELETS Companion sterile spikelets represented by barren pedicels.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets lanceolate (19), or oblong (1), or ovate (2); dorsally compressed; 3.5–6.137–11 mm long; falling entire; deciduous from the base (2), or with accessory branch structures. Spikelet callus brief (15), or oblong (2), or cuneate (1), or linear (2); pubescent (7), or pilose (9), or bearded (4); base obtuse (16), or acute (1), or pungent (3); attached obliquely (1/1).

GLUMES Glumes exceeding apex of florets (1/1); firmer than fertile lemma. Lower glume lanceolate (1), or oblong (17), or ovate (2); chartaceous (2), or coriaceous; without keels; 7–8 -veined (13/17), or 9 -veined (17/17). Lower glume lateral veins obscure (2), or distinct (18). Lower glume surface smooth (19), or asperulous (1); without pits; glabrous (1), or pubescent (12), or pilose (7), or villous (1); without hair tufts (19), or with an apical beard (1). Lower glume apex entire (19), or dentate (1); 2 -fid (1/1); truncate (17/17). Upper glume lanceolate (2), or oblong (17), or ovate (1); chartaceous (2/14), or coriaceous (14/14); without keels (19), or 1-keeled (1); 3 -veined (1/15), or 5 -veined (14/15). Upper glume surface smooth (19), or asperulous (1); glabrous, or pubescent (1). Upper glume apex acute (14/14).

FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret lanceolate (1), or oblong (19); hyaline; 2 -veined (19), or 3 -veined (1). Fertile lemma oblong; hyaline; without keel; wingless; 1–2 -veined (1/15), or 3 -veined (13/15). Lemma surface smooth (19), or asperulous (1); unwrinkled; without grooves; glabrous (19), or pilose (1). Lemma margins eciliate (4), or ciliolate (16). Lemma apex entire (2), or dentate (2), or lobed (16); 2 -fid (18/18); incised 0.2 of lemma length; muticous (2), or awned; 1 -awned. Principal lemma awn apical (2), or from a sinus (18); straight (5), or geniculate (9), or bigeniculate (11). Column of lemma awn glabrous (3/18), or hispidulous (14/18), or pubescent (2/18). Palea absent or minute.

FLOWER Lodicules 2 (17/17). Anthers 3 (15/15). Stigmas 2 (1/1).

FRUIT Caryopsis with adherent pericarp (1/1); oblanceolate (1/1).

DISTRIBUTION Africa (6), or Australasia (1), or North America (9), or South America (13).

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