Iseilema siamense

HABIT Annual. Culms rambling; 15–18 cm long. Culm-nodes glabrous. Leaf-sheaths keeled; glabrous on surface. Ligule an eciliate membrane. Leaf-blades spreading, or reflexed; 2–4 cm long; 4–5 mm wide; glaucous. Leaf-blade surface glabrous. Leaf-blade margins tuberculate-ciliate. Leaf-blade apex acute.

INFLORESCENCE Synflorescence compound; linear; 6–9 cm long. Inflorescence composed of racemes; terminal and axillary; deciduous as a whole; subtended by a spatheole; enclosed. Spatheole lanceolate, or ovate; 1.5–1.8 cm long; herbaceous; tuberculate (on midnerve); glabrous. Peduncle 0.8–1.2 cm long.

Racemes 1; single; oblong; bearing few fertile spikelets; bearing 1 fertile spikelets on each. Rhachis internodes linear. Raceme-bases brief (truncate).

Spikelets in threes (basal paired). Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 2 in the cluster. Pedicels filiform; 4–6 mm long; scaberulous; ciliate.

STERILE SPIKELETS Basal sterile spikelets well-developed; 4 in number; forming an involucre about the fertile; with both pairs arising at about the same level; pedicelled; deciduous with the fertile. Basal sterile spikelet pedicels oblong; 1.5–2 mm long. Basal sterile spikelets barren; lanceolate, or oblong; 6–7 mm long; smaller than fertile. Basal sterile spikelet glumes herbaceous; glabrous; scabrous on margins.

Companion sterile spikelets well-developed; male; linear, or lanceolate; 5–6 mm long; shorter than fertile; separately deciduous. Companion sterile spikelet glumes chartaceous; tuberculate (on keels); glabrous; muticous. Companion sterile spikelet lemmas 2; enclosed by glumes.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets lanceolate; dorsally compressed; 9 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus pilose. Spikelet callus hairs 2.5 mm long.

GLUMES Glumes dissimilar; firmer than fertile lemma. Lower glume elliptic; 1 length of spikelet; cartilaginous; without keels; keel-less except near apex; 12 -veined. Lower glume primary vein scaberulous. Lower glume surface asperulous; rough above. Lower glume apex acuminate. Upper glume lanceolate; 1 length of spikelet; cartilaginous; 3–5 -veined.

FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret hyaline. Fertile florets female. Fertile lemma linear; 3 mm long; membranous; 1 -veined. Lemma apex entire; awned; 1 -awned. Principal lemma awn geniculate; 20–25 mm long overall; with twisted column. Column of lemma awn glabrous. Palea absent or minute.

FLOWER Anthers 3; 1.5 mm long.

FRUIT Caryopsis with adherent pericarp; obovoid; 3–3.5 mm long.

DISTRIBUTION Asia-tropical: Indo-China.

NOTES Andropogoneae. CEH.

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