Tripsacum dactyloides

HABIT Perennial; caespitose. Rhizomes short; knotty. Butt sheaths pilose. Culms erect, or geniculately ascending; robust, or of moderate stature; 150–400 cm long; 30–40 mm diam.; with prop roots. Culm-internodes solid. Leaves basal and cauline. Leaf-sheaths glabrous on surface. Ligule a ciliolate membrane; 1 mm long. Leaf-blades 60–120 cm long; 18–60 mm wide. Leaf-blade surface scaberulous; rough adaxially; glabrous. Leaf-blade margins scabrous.

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

Racemes 1–10; single, or paired, or digitate; erect; arcuate; smoothly terete; unilateral; 12–25 cm long. Central inflorescence axis 0.5–1.5 cm long. Rhachis (female) fragile at the nodes; subcylindrical and excavated; 3–5.5 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, or sessile and pedicelled; 2 in a cluster. Pedicels (male) 0–2 mm long.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets ovate; dorsally compressed; 6–8 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; 3 mm long; hyaline. Fertile florets female. Fertile lemma oblong; 8 mm long; hyaline; without keel. Palea hyaline.

FLOWER Styles connate below.

MALE Male spikelets distinct from female; with free pedicels; all deciduous together; 6–12 mm long; glabrous, or hairy; obtuse, or acute, or dentate. Male spikelet glumes 2; coriaceous; muticous.

DISTRIBUTION Asia-tropical: Malesia. Australasia: Australia. North America: north-central USA, northeast USA, south-central USA, southeast USA, and 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.