Andropogon selloanus

HABIT Perennial; caespitose. Culms erect; 40–110 cm long; 2–3.5 mm diam. Culm-internodes solid. Culm-nodes glabrous. Lateral branches sparse. Leaves mostly basal. Leaf-sheaths keeled; glabrous on surface. Ligule a ciliolate membrane; 0.5–1 mm long. Leaf-blades flat, or conduplicate; 20–40 cm long; 3–5 mm wide. Leaf-blade midrib keeled beneath. Leaf-blade apex obtuse; hooded.

INFLORESCENCE Synflorescence compound; scanty. Inflorescence composed of racemes; terminal and axillary; subtended by a spatheole. Spatheole linear; 5–9 cm long. Peduncle pilose above.

Racemes 3–5; digitate; 3–6 cm long. Rhachis fragile at the nodes; plumose on surface; plumose on margins. Rhachis hairs lengthening towards internode tip; 5–10 mm long. Rhachis internodes linear; 2–2.8 mm long. Rhachis internode tip transverse; cupuliform; with simple rim.

Spikelets ascending; in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels linear; 3.5–3.8 mm long; plumose; with 5–10 mm long hairs.

STERILE SPIKELETS Companion sterile spikelets represented by single glumes; linear; 0.6–1.2 mm long; shorter than fertile. Companion sterile spikelet glumes chartaceous; glabrous; acute; muticous.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets lanceolate; dorsally compressed; 3.5–4 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus bearded; base obtuse; inserted. Spikelet callus hairs 4–5 mm long.

GLUMES Glumes dissimilar; exceeding apex of florets; firmer than fertile lemma. Lower glume lanceolate; 1 length of spikelet; membranous; 2-keeled; keeled laterally. Lower glume intercarinal veins absent. Lower glume surface concave. Upper glume linear; membranous; 1-keeled. Upper glume muticous.

FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret oblong; 2–2.5 mm long; hyaline; 2 -veined; ciliate on margins; fringed above. Fertile lemma lanceolate; 1.5–2 mm long; hyaline; without keel. Lemma apex entire; acuminate; muticous, or mucronate. Palea absent or minute.

FLOWER Anthers 3; 0.6 mm long.

FRUIT Caryopsis linear; 1.7 mm long.

DISTRIBUTION North America: Mexico. South America: Mesoamericana, Caribbean, northern South America, western South America, Brazil, and southern South America.

NOTES Andropogoneae. Fl Costaric 1993.

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