GrassBase - The Online World Grass Flora


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

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

Stipa ameghinoi

HABIT Perennial; caespitose. Butt sheaths purple. Culms erect; 10–25 cm long; 0.5–0.7 mm diam.; 2–3 -noded. Culm-internodes smooth; distally glabrous, or pubescent. Culm-nodes constricted; glabrous. Leaf-sheaths mostly shorter than adjacent culm internode; smooth; glabrous on surface. Leaf-sheath oral hairs lacking, or pubescent. Ligule a ciliolate membrane; 1 mm long. Leaf-blades straight, or curved; conduplicate; 2–8 cm long; 0.4–0.7 mm wide. Leaf-blade surface smooth; glabrous. Leaf-blade apex pungent.

INFLORESCENCE Inflorescence a panicle; comprising 6–10 fertile spikelets; embraced at base by subtending leaf.

Panicle open; oblong; 3–5 cm long; 1–1.5 cm wide; bearing few spikelets.

Spikelets solitary. Fertile spikelets pedicelled. Pedicels 3–5 mm long; ciliate; hairy above.

FERTILE SPIKELETS Spikelets comprising 1 fertile florets; without rhachilla extension. Spikelets lanceolate; subterete; 17–24 mm long; breaking up at maturity; disarticulating below each fertile floret. Floret callus evident; curved; pubescent; pungent.

GLUMES Glumes persistent; similar; exceeding apex of florets; thinner than fertile lemma. Lower glume lanceolate; 17–24 mm long; 1.05 length of upper glume; membranous; without keels; 3 -veined. Lower glume apex acuminate. Upper glume lanceolate; 16–23 mm long; membranous; without keels; 3 -veined. Upper glume apex acuminate.

FLORETS Fertile lemma lanceolate; subterete; 7–7.5 mm long; coriaceous; without keel; 5 -veined. Lemma surface pilose; hairy below. Lemma margins convolute; covering most of palea. Lemma hairs 1–3 mm long. Lemma apex dentate; 2 -fid; with lobes 1 mm long; awned; 1 -awned. Principal lemma awn from a sinus; geniculate; 25–35 mm long overall; with twisted column. Column of lemma awn 9–12 mm long; plumose. Palea 5–5.5 mm long; 2 -veined; without keels. Palea surface pilose.

FLOWER Lodicules 3. Anthers 3; yellow; anther tip smooth. Stigmas 2. Styles free to the base. Ovary glabrous.

FRUIT Caryopsis with adherent pericarp; fusiform. Hilum linear.

DISTRIBUTION South America: southern South America.

NOTES Stipeae. Fl Pat 1995.

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