Deyeuxia trichodonta

HABIT Perennial; caespitose. Butt sheaths yellow; glabrous. Basal innovations intravaginal. Culms erect, or geniculately ascending; 15–38 cm long; 3 -noded; with 0.5 of their length below uppermost node; without nodal roots. Culm-internodes similar in length; terete; yellow; concolorous; striate; smooth. Culm-nodes flush with internodes; without obvious supra-nodal ridge; pallid; glabrous. Lateral branches lacking. Leaves mostly basal. Leaf-sheaths loose; unthickened at base; open for most of their length; without keel; striately veined; smooth; glabrous on surface. Ligule an eciliate membrane; 1 mm long; membranous; lacerate. Collar concolorous; glabrous. Leaf-blade base symmetrical. Leaf-blades tapering towards tip; involute; 1.5–2.5 mm wide; concolorous. Leaf-blade midrib indistinct; scarcely raised beneath. Leaf-blade venation distinct. Leaf-blade surface smooth; glabrous; hairless throughout. Leaf-blade margins scaberulous. Leaf-blade apex acute; hooded.

INFLORESCENCE Inflorescence a panicle. Peduncle terete.

Panicle open; oblong, or ovate; continuous; effuse; straight; 6–10 cm long; 2–3 cm wide; 0.33 of culm length. Primary panicle branches spreading; moderately spaced; 3 -nate; whorled at most nodes; 0.8–2 cm long; with lower 0.1–0.2 length of panicle; bearing 4–6 fertile spikelets on each lower branch. Panicle axis dominant, or distinct; 6–10 noded; with lower internodes 2.5 cm long; with rounded ribs; glandular; smooth. Panicle branches terete; multilateral; bearing approximate spikelets; glandular; with occasional prickles.

Spikelets ascending; solitary. Fertile spikelets pedicelled. Pedicels linear; 0.2–0.5 length of fertile spikelet; tip widened.

FERTILE SPIKELETS Spikelets comprising 1 fertile florets; with a barren rhachilla extension. Spikelets lanceolate; with obtuse base; laterally compressed; compressed moderately; 5 mm long; breaking up at maturity; disarticulating below each fertile floret. Floret callus pubescent; hairy on the margins and in 2 tufts; with subequal hairs. Floret callus hairs 0.5–1 mm long; 0.2–0.4 length of lemma (the two specimens available for inspection had callus hairs of this dimenstion. The original description however indicated that the hairs were two thirds the length of the lemma, but this has been found to refer to rhachilla extension).

GLUMES Glumes persistent; similar; subequal in width; exceeding apex of florets; firmer than fertile lemma. Lower glume lanceolate; symmetrical; not clasping; 5.5 mm long; 1.1 length of upper glume; 1 length of spikelet; membranous; purple; 1-keeled; 1 -veined. Lower glume primary vein extending to apex; pectinately ciliate. Lower glume lateral veins absent. Lower glume inner surface glabrous. Lower glume margins flat. Lower glume apex acute. Upper glume lanceolate; symmetrical; dorsally convex in profile; 3.8–5 mm long; 1–1.1 length of adjacent fertile lemma; 1 length of spikelet; narrower than lemma; pallid, or yellow; eglandular; 1-keeled; 3 -veined. Upper glume primary vein obscure; smooth. Upper glume lateral veins absent. Upper glume surface smooth; inner surface glabrous. Upper glume margins smooth. Upper glume apex acute.

FLORETS Fertile lemma lanceolate; widest at 0.33 of its length from base; symmetrical; laterally compressed; dorsally convex along back; lanceolate in profile; 3.75–4.5 mm long; 1 mm wide; membranous; yellow; concolorous; without keel; rounded throughout; 0 -veined. Lemma midvein simple. Lemma lateral veins obscure; absent or obscure below. Lemma surface scabrous; rough above; unwrinkled, or rugulose; with basal hair tufts near margin; inner surface glabrous. Lemma apex dentate; 5 -fid; with simple equal lobes; with filiform lobes; with lobes 0.5–0.8 mm long; incised 0.2 of lemma length; acuminate; awned; 1 -awned. Principal lemma awn median; dorsal; arising 0.35–0.4 way up back of lemma; geniculate; ascending; simple at base; subterete below; stiff; attenuate; 5 mm long overall; 1.3 length of lemma; with 3 mm long limb; clearly exserted from spikelet; with twisted column; persistent; limb scaberulous, or scabrous. Column of lemma awn 2 mm long; 0.4 length of limb; scabrous. Palea present; free; embraced by lemma; linear; with flaps narrower than body; 2.5–3.2 mm long; 0.8 length of lemma; membranous; of uniform consistency; 2-keeled. Palea keels extending to apex; 0.7–1 mm apart; scaberulous. Palea surface scaberulous. Palea apex erose; truncate. Rhachilla extension 1.6 mm long; 0.3–0.4 length of fertile floret; approximately straight; pubescent; hairy throughout; with 0.5–3 mm long hairs.

FLOWER Lodicules 2. Anthers 3; linear; 3 mm long; eventually exserted; dehiscent by a longitudinal slit; pallid; anther tip smooth. Stigmas 2; retained within floret; white. Styles 1 mm long. Ovary glabrous.

FRUIT Disseminule comprising a caryopsis.

DISTRIBUTION South America: western South America and southern South America.

NOTES Aveneae. KTH 2006.

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