Rottboellia laevispica

HABIT Annual. Culms geniculately ascending; 100–150 cm long; 3 mm diam.; rooting from lower nodes. Culm-internodes terete, or channelled; striate. Leaf-sheaths keeled; smooth, or papillose. Leaf-sheath oral hairs lacking, or ciliate. Ligule a ciliolate membrane; 0.5–1 mm long; brown; obtuse. Leaf-blades linear, or lanceolate; 15–40 cm long; 8–16 mm wide; flaccid; mid-green, or glaucous. Leaf-blade surface smooth, or scaberulous; rough abaxially; glabrous; hairless throughout, or except near base. Leaf-blade margins scabrous. Leaf-blade apex acuminate.

INFLORESCENCE Inflorescence composed of racemes.

Racemes 1; single; smoothly terete; 10–15 cm long; 2–3 mm wide. Rhachis fragile at the nodes; glabrous on surface; terminating in a sterile spikelet. Rhachis internodes cuneate; 1 length of fertile spikelet. Rhachis internode tip transverse; crateriform; with simple rim.

Spikelets appressed; in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels free, or fused to internode; united wholly, or below; oblong; flattened; 1 length of fertile spikelet.

STERILE SPIKELETS Companion sterile spikelets rudimentary; comprising 2 subequal glumes without lemmas; lanceolate; shorter than fertile.

Apical sterile spikelets barren.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets oblong; dorsally compressed; 7–10 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus 1 mm long; glabrous; base truncate; with central peg; attached transversely.

GLUMES Glumes dissimilar; exceeding apex of florets; firmer than fertile lemma. Lower glume oblong; 1 length of spikelet; coriaceous; 2-keeled; winged on keel; winged narrowly; winged above. Lower glume lateral veins prominent. Lower glume surface flat; asperulous; rough above. Upper glume ovate; chartaceous; 1-keeled; 9–11 -veined. Upper glume primary vein scaberulous. Upper glume apex acute.

FLORETS Basal sterile florets male; with palea. Lemma of lower sterile floret ovate; 1 length of fertile lemma; membranous; 3–5 -veined. Fertile lemma ovate; 6–8 mm long; hyaline; without keel; 3 -veined. Palea 1 length of lemma.

FLOWER Anthers 3; 2–3 mm long.

DISTRIBUTION Asia-temperate: China.

NOTES Andropogoneae. Keng 1996.

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