Helictotrichon arctum

HABIT Perennial; caespitose. Culms erect; 15–30 cm long. Ligule an eciliate membrane; 1 mm long. Leaf-blades filiform, or linear; involute; 0.4–0.5 mm wide. Leaf-blade surface smooth; glabrous.

INFLORESCENCE Inflorescence a panicle.

Panicle contracted; linear; 6.5–9 cm long. Primary panicle branches appressed.

Spikelets solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 3 fertile florets; with diminished florets at the apex. Spikelets oblong; laterally compressed; 8–9.5 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes 1.5–2 mm long; pubescent; hairy above. Floret callus pilose.

GLUMES Glumes persistent; similar; shorter than spikelet; thinner than fertile lemma. Lower glume lanceolate; 4–4.5 mm long; 0.75 length of upper glume; herbaceous; much thinner above; much thinner on margins; 1-keeled; 1 -veined. Lower glume lateral veins absent. Lower glume apex acuminate. Upper glume lanceolate, or oblong; 5.5–6 mm long; 0.75 length of adjacent fertile lemma; herbaceous; much thinner above; with hyaline margins; 1-keeled; 3 -veined. Upper glume apex acuminate.

FLORETS Fertile lemma elliptic; 7–8 mm long; herbaceous; much thinner above; much thinner on margins; without keel; 5 -veined. Lemma surface asperulous; rough above. Lemma apex dentate; 2 -fid; awned; 3 -awned. Principal lemma awn dorsal; geniculate; 9–16 mm long overall; with twisted column. Lateral lemma awns arising on apex of lobes; 1 mm long; shorter than principal. Apical sterile florets resembling fertile though underdeveloped.

FLOWER Anthers 3. Ovary pubescent on apex.

FRUIT Caryopsis with adherent pericarp; hairy at apex. Hilum linear.

DISTRIBUTION Asia-temperate: Arabia.

NOTES Aveneae. TAC 1997.

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