Tripsacum andersonii

HABIT Perennial. Rhizomes short. Butt sheaths pilose. Culms geniculately ascending, or decumbent; robust; 300–500 cm long; 20–30 mm diam.; without nodal roots, or with prop roots. Culm-internodes distally glabrous. Leaf-sheaths glabrous on surface. Ligule a ciliolate membrane; 1 mm long. Leaf-blades 60–120 cm long; 40–100 mm wide. Leaf-blade surface pubescent; sparsely hairy; hairy adaxially; with tubercle-based hairs. Leaf-blade apex acuminate.

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

Racemes 3–8; digitate; erect; smoothly terete; unilateral; 15–20 cm long; bearing 4–12 fertile spikelets on each. Rhachis (female) fragile at the nodes; subcylindrical and excavated; 4–5.5 mm wide. Spikelet packing abaxial. Rhachis internodes oblong; 6–10 mm long; 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 and pedicelled; 2 in a cluster. Pedicels (male) 1–3 mm long.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets ovate; dorsally compressed; 8–10 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus base truncate; with central peg; attached transversely.

GLUMES Glumes dissimilar; reaching apex of florets; firmer than fertile lemma; shiny. Lower glume ovate; 1 length of spikelet; indurate; without keels. Lower glume apex acute. Upper glume ovate; cartilaginous; without keels. Upper glume apex acute.

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

MALE Male spikelets distinct from female; with free pedicels; all deciduous together; 6–10 mm long; hairy; acute. Male spikelet glumes 2; coriaceous; muticous.

DISTRIBUTION Africa: west tropical, west-central tropical, east tropical, and western Indian ocean. Asia-tropical: India, Malesia, and Papuasia. Pacific: southwestern, south-central, northwestern, and north-central. North America: Mexico. South America: Mesoamericana, Caribbean, northern South America, western South America, and Brazil.

NOTES Andropogoneae. Fl Meso-Am 1995.

Please cite this publication as detailed in How to Cite Version: 3rd February 2016.