Tripsacum lanceolatum

HABIT Perennial. Butt sheaths pilose. Culms erect; 50–200 cm long. Leaf-sheaths glabrous on surface; outer margin glabrous, or hairy. Ligule a ciliolate membrane. Leaf-blades flat, or conduplicate; 20–45 cm long; 10–20 mm wide. Leaf-blade surface glabrous, or pubescent; hairy adaxially. Leaf-blade apex acuminate.

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

Racemes 2–5(–9); digitate; arcuate; smoothly terete; unilateral; 5–20 cm long. Rhachis fragile at the nodes; subcylindrical and excavated. Spikelet packing abaxial. Rhachis internodes oblong; 4–6 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 2–3.5 mm long.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets ovate; dorsally compressed; 4–6 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; (5–)7–8(–9) mm long; hairy. Male spikelet glumes 2; muticous.

DISTRIBUTION North America: southwest USA and Mexico. South America: Mesoamericana.

NOTES Andropogoneae. Fl Nov Gal 1994.

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