Helictotrichon planifolium

HABIT Perennial. Rhizomes elongated. Basal innovations extravaginal. Culms 60–100 cm long. Leaf-sheaths tubular for much of their length; with 0.5 of their length closed. Ligule a ciliolate membrane; 0.5 mm long; truncate. Leaf-blades flat; 20–35 cm long; (2–)3–4(–7) mm wide; flaccid. Leaf-blade venation without layer of subepidermal sclerenchyma masking vein striation. Leaf-blade surface ribbed.

INFLORESCENCE Inflorescence a panicle.

Panicle open; linear, or oblong; 6–15 cm long. Primary panicle branches bearing 1–5 fertile spikelets on each lower branch.

Spikelets solitary. Fertile spikelets pedicelled. Pedicels clavate.

FERTILE SPIKELETS Spikelets comprising 3–4 fertile florets; with diminished florets at the apex. Spikelets oblong; laterally compressed; 11–14 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes 1.5–2.5 mm long; pilose; with 1.5–5 mm long hairs. Floret callus pilose. Floret callus hairs 2–2.5 mm long.

GLUMES Glumes persistent; similar; shorter than spikelet; thinner than fertile lemma. Lower glume elliptic; 7–9 mm long; 0.9 length of upper glume; membranous; 1-keeled; 1 -veined. Lower glume lateral veins absent. Lower glume apex acute. Upper glume elliptic; 8–11 mm long; 1.1 length of adjacent fertile lemma; membranous; 1-keeled; 3 -veined. Upper glume apex acute.

FLORETS Fertile lemma elliptic; 7–10 mm long; cartilaginous; without keel; 5–7 -veined. Lemma apex dentate; 2 -fid; awned; 1 -awned. Principal lemma awn dorsal; arising 0.5 way up back of lemma; geniculate; subterete below; 10–15 mm long overall; with twisted column. Palea 6–9 mm long. Palea keels ciliolate. Apical sterile florets resembling fertile though underdeveloped.

FLOWER Anthers 3; 5 mm long. Ovary pubescent on apex.

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

DISTRIBUTION Europe: southwestern.

NOTES Aveneae. Fl Eur 1995.

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