Helictotrichon macrorhinum

HABIT Perennial; caespitose. Butt sheaths distinctly ribbed; glabrous. Culms erect; 50–100 cm long; 1–2.5 mm diam.; 2–4 -noded. Culm-internodes terete, or elliptical in section; ridged; smooth, or scaberulous. Culm-nodes glabrous. Leaf-sheaths ribbed; smooth, or scaberulous. Ligule an eciliate membrane; 6–17 mm long; acute. Leaf-blades flat, or involute; 15–25 cm long; 1.5–4 mm wide. Leaf-blade surface ribbed; grooved adaxially and abaxially; smooth to scabrous; pubescent; hairy adaxially.

INFLORESCENCE Inflorescence a panicle.

Panicle open, or contracted; 20–40 cm long. Primary panicle branches 1–3 -nate; 4–8 cm long.

Spikelets solitary. Fertile spikelets pedicelled. Pedicels 10–20 mm long.

FERTILE SPIKELETS Spikelets comprising 4–5 fertile florets; with a barren rhachilla extension, or with diminished florets at the apex. Spikelets oblong; laterally compressed; 10–17 mm long; breaking up at maturity; disarticulating below each fertile floret.

GLUMES Glumes persistent; similar; shorter than spikelet; thinner than fertile lemma. Lower glume lanceolate; 3.9–6.3 mm long; 0.9 length of upper glume; membranous; much thinner on margins; 1-keeled; 3–4 -veined. Lower glume apex acute, or acuminate. Upper glume lanceolate; 4.2–7 mm long; 0.9–1.2 length of adjacent fertile lemma; membranous; with hyaline margins; 1-keeled; 5 -veined. Upper glume surface smooth, or papillose. Upper glume apex acute.

FLORETS Fertile lemma elliptic; 3.5–7.9 mm long; cartilaginous; much thinner above; without keel; 7 -veined. Lemma surface papillose; rough below. Lemma apex dentate; 4 -fid; with outer lobes shorter; with lobes 0.5–1.15 mm long; awned; 1 -awned. Principal lemma awn dorsal; arising 0.4–0.5 way up back of lemma; geniculate; 10–19 mm long overall; with 6.5–13.5 mm long limb; with a straight or slightly twisted column. Column of lemma awn 3.5–6.8 mm long; scabrous. Palea 0.66–0.95 length of lemma. Palea keels ciliate. Palea surface papillose. Apical sterile florets resembling fertile though underdeveloped.

FLOWER Lodicules 2; 1–2.2 mm long; membranous; glabrous; acute. Anthers 3; 2.7–3 mm long; eventually exserted, or retained within floret. Ovary glabrous.

FRUIT Caryopsis with adherent pericarp; 1.5–1.95 mm long; light brown; glabrous. Embryo 0.15–0.2 length of caryopsis. Hilum linear; 0.3–0.4 length of caryopsis.

DISTRIBUTION Australasia: Australia.

NOTES Aveneae. Jacobs & Lap 1994.

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