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.

Tripsacum

HABIT Perennial. Rhizomes absent (4), or short (8), or elongated (2). Culms erect (10), or geniculately ascending (7), or decumbent (2); robust (10/13), or of moderate stature (4/13); 50–283.4–500 cm long; without nodal roots (2/3), or with prop roots (3/3). Leaf-sheath auricles absent (13), or erect (1). Ligule a ciliolate membrane. Leaf-blade base without a false petiole (11), or with a false petiole (3). Leaf-blades linear (11), or lanceolate (3); herbaceous (13), or coriaceous (1).

INFLORESCENCE Monoecious; with male and female spikelets in the same inflorescence. Inflorescence composed of racemes; terminal and axillary.

Racemes single (5), or paired (4), or digitate (12); erect (7), or ascending (3), or spreading (1), or drooping (3); unilateral; bearing 4–12 fertile spikelets on each (1/1). Rhachis fragile at the nodes; subcylindrical and excavated. Spikelet packing abaxial. Rhachis internodes oblong; adherent to upper glume of sessile spikelet. Rhachis internode tip transverse; crateriform.

Sexes segregated; on bisexual branches; with male above. Spikelets sunken; solitary. Fertile spikelets sessile. Male spikelets sessile (8), or sessile and pedicelled (8); 2 in a cluster.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets oblong (1), or ovate (13); dorsally compressed; 3–6.016–10 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus base truncate; with central peg; attached transversely.

GLUMES Glumes reaching apex of florets; firmer than fertile lemma. Lower glume ovate; indurate; without keels. Lower glume surface without pits. Lower glume apex acute (7/9), or acuminate (2/9). Upper glume ovate; cartilaginous; without keels. Upper glume apex acute (9/9).

FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret oblong; hyaline. Fertile florets female. Fertile lemma oblong; hyaline; without keel; wingless. Lemma surface unwrinkled; without grooves. Palea hyaline.

FLOWER Anthers 3 (1/1).

MALE Male spikelets distinct from female; lanceolate (2/2), or elliptic (2/2). Male spikelet glumes 2; muticous.

DISTRIBUTION Africa (1), or Tropical Asia (2), or Australasia (1), or Pacific (1), or North America (12), or South America (13).

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