GrassBase - The Online World Grass Flora

Descriptions

W.D. Clayton, M. Vorontsova, K.T. Harman & H. Williamson

© Copyright The Board of Trustees, Royal Botanic Gardens, Kew.

Festuca roblensis

HABIT Perennial; caespitose; clumped densely. Butt sheaths persistent and investing base of culm; with fibrous dead sheaths. Basal innovations intravaginal. Culms erect; 100–130 cm long; 1.6–2.6 mm diam. Leaf-sheaths smooth, or scaberulous. Leaf-sheath auricles absent. Ligule an eciliate membrane; 1.3–5 mm long; lacerate. Leaf-blades flat, or involute; 30–55 cm long; 1.5–3.6 mm wide. Leaf-blade midrib conspicuous. Leaf-blade surface ribbed; grooved adaxially; smooth, or scaberulous; rough abaxially. Leaf-blade apex attenuate.

INFLORESCENCE Inflorescence a panicle. Peduncle smooth, or scaberulous above.

Panicle open; ovate; 16–26 cm long. Primary panicle branches 2 -nate; bearing 2–7 fertile spikelets on each lower branch. Panicle branches scaberulous.

Spikelets solitary. Fertile spikelets pedicelled. Pedicels 3–8 mm long.

FERTILE SPIKELETS Spikelets comprising 3–6 fertile florets; with diminished florets at the apex. Spikelets oblong; laterally compressed; 13–20 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes scaberulous.

GLUMES Glumes persistent; similar; shorter than spikelet. Lower glume lanceolate; 2.5–4.8 mm long; 0.33–0.5 length of upper glume; chartaceous; much thinner on margins; without keels; 1 -veined. Lower glume lateral veins absent. Lower glume apex acute. Upper glume lanceolate; 3.8–6 mm long; 0.33–0.5 length of adjacent fertile lemma; chartaceous; with hyaline margins; without keels; 3 -veined. Upper glume apex acute.

FLORETS Fertile lemma lanceolate; 9.7–12.7 mm long; chartaceous; without keel; 5 -veined. Lemma surface smooth, or scaberulous; rough above. Lemma apex acute; awned; 1 -awned. Principal lemma awn 0.5–3.7 mm long overall. Palea 2 -veined. Apical sterile florets resembling fertile though underdeveloped.

FLOWER Lodicules 2; 1–1.5 mm long. Anthers 3; 4–5.5 mm long. Ovary glabrous.

FRUIT Caryopsis with adherent pericarp; 5.5–7 mm long. Hilum linear.

DISTRIBUTION North America: Mexico.

NOTES Poeae. Gonz.-Ledesma 2004.

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