Nassella arechavaletae

HABIT Perennial; caespitose; clumped loosely. Butt sheaths persistent and investing base of culm; with fibrous dead sheaths. Basal innovations extravaginal. Culms erect; 35–90 cm long; 1–2 mm diam.; 2–3 -noded. Culm-internodes smooth; distally glabrous. Culm-nodes glabrous, or pubescent. Lateral branches lacking. Leaf-sheaths striately veined; pubescent; outer margin hairy. Leaf-sheath oral hairs bearded. Ligule an eciliate membrane. Leaf-blades convolute; 10–40 cm long; 2–4 mm wide. Leaf-blade venation with 22–40 secondary veins. Leaf-blade surface scabrous; rough adaxially; glabrous, or pilose; sparsely hairy; hairy abaxially. Leaf-blade apex acute.

INFLORESCENCE Inflorescence a panicle; subtended by an inflated leaf-sheath; embraced at base by subtending leaf.

Panicle open; linear; 10–25 cm long. Primary panicle branches 2 -nate; bearing 1–5 fertile spikelets on each lower branch. Panicle axis smooth.

Spikelets solitary. Fertile spikelets pedicelled. Pedicels angular; 5–25 mm long; scabrous; tip widened.

FERTILE SPIKELETS Spikelets comprising 1 fertile florets; without rhachilla extension. Spikelets lanceolate; subterete; 32–38 mm long; breaking up at maturity; disarticulating below each fertile floret. Floret callus elongated; curved; 5–6 mm long; pubescent; pungent.

GLUMES Glumes persistent; similar; with lower narrower than upper; exceeding apex of florets; thinner than fertile lemma. Lower glume lanceolate; 32–38 mm long; 1.3 length of upper glume; membranous; purple; 1-keeled; 3 -veined. Lower glume apex setaceously attenuate. Upper glume lanceolate; 25–30 mm long; membranous; purple; without keels; 5 -veined. Upper glume apex setaceously attenuate.

FLORETS Fertile lemma lanceolate; subterete; 7.5–8 mm long; coriaceous; pallid; without keel. Lemma midvein pubescent; hairy below. Lemma surface asperulous. Lemma margins convolute; covering most of palea. Lemma apex with a membranous corona and surmounted by a ring of hairs; with this appendage 2 mm long; awned; 1 -awned. Principal lemma awn bigeniculate; constricted at base (of corona); 135–150 mm long overall; with twisted column. Column of lemma awn pubescent. Palea 2 mm long; hyaline; 0 -veined; without keels.

FLOWER Lodicules 2. Anthers 3. Stigmas 2. Ovary glabrous.

FRUIT Caryopsis with adherent pericarp; fusiform; 11–16 mm long. Hilum linear.

DISTRIBUTION South America: Brazil and southern South America.

NOTES Stipeae. Spegazzini 1996.

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