Andropogon columbiensis

HABIT Annual; caespitose. Glands capitate. Culms slender; 14–27 cm long. Culm-internodes 0.7–3.5 cm long. Culm-nodes glabrous. Lateral branches lacking. Leaves mostly basal. Leaf-sheaths 1.8–5.6 cm long; striately veined; pilose. Ligule an eciliate membrane, or a ciliolate membrane; 3.2–4.3 mm long; erose. Leaf-blades filiform, or linear; conduplicate; 4.5–15.3 cm long; 1 mm wide; coriaceous. Leaf-blade surface scaberulous; rough on both sides; glabrous. Leaf-blade margins scaberulous. Leaf-blade apex acuminate.

INFLORESCENCE Inflorescence composed of racemes; terminal; exserted, or embraced at base by subtending leaf.

Racemes 1; single; (2.5–)3.5–4 cm long. Rhachis fragile at the nodes; villous on margins. Rhachis hairs 3–4 mm long. Rhachis internodes cuneate. Rhachis internode tip oblique; crateriform; with simple rim.

Spikelets appressed; in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels cuneate; 3.1–3.6 mm long; villous; with 4 mm long hairs.

STERILE SPIKELETS Companion sterile spikelets well-developed; containing empty lemmas; lanceolate; dorsally compressed; 5.5–9.2 mm long; longer than fertile; deciduous with the fertile. Companion sterile spikelet glumes membranous; 5.5–9.2 mm long; 11–19 -veined; glabrous; acute; awned; one glume awned; with 5–9 mm long awn. Companion sterile spikelet lemmas 1; enclosed by glumes; (2–)3.8–4 mm long.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets linear; laterally compressed; 4.5–4.8 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus bearded; base obtuse; inserted.

GLUMES Glumes dissimilar; exceeding apex of florets; firmer than fertile lemma. Lower glume linear; 1 length of spikelet; coriaceous; 3 -veined (confused with dorsal keels?). Lower glume surface pubescent. Lower glume hairs 1.6 mm long. Upper glume ovate; (3.8–)4.4–4.8 mm long; chartaceous; 1-keeled; 1 -veined. Upper glume lateral veins absent. Upper glume surface glabrous, or pubescent; hairy above. Upper glume awned; 1 -awned. Upper glume awn 5.8–17.2 mm long.

FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret lanceolate; 3.4–3.7 mm long; hyaline; puberulous; hairy above. Fertile lemma lanceolate; 3–3.2 mm long; hyaline; without keel; 3 -veined. Lemma margins ciliolate. Lemma apex awned; 1 -awned. Principal lemma awn geniculate; 21–40 mm long overall; with twisted column. Column of lemma awn glabrous.

FLOWER Lodicules 2. Anthers 3; 1.2 mm long; brown.

DISTRIBUTION South America: western South America.

NOTES Andropogoneae. Gir.-Canas 2014.

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