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.

Tridens

HABIT Perennial. Rhizomes absent (12), or short (3), or elongated (2). Culms erect (11/11); robust (1/1); 20–75.73–180 cm long. Lateral branches lacking (2/2). Ligule an eciliate membrane (1), or a ciliate membrane (4), or a fringe of hairs (12).

INFLORESCENCE Inflorescence a panicle, or composed of racemes (1); terminal (16), or terminal and axillary (1).

Panicle open (10), or contracted (6), or spiciform (1).

Racemes borne along a central axis (1/1).

Spikelets appressed (2/2), or ascending (1/2); solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 3–7–15 fertile florets; with diminished florets at the apex. Spikelets elliptic (1), or oblong (13), or ovate (2), or orbicular (1), or cuneate (1); laterally compressed; 3–7.391–15 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes definite. Floret callus glabrous (1/11), or pubescent (10/11).

GLUMES Glumes persistent; shorter than spikelet (16), or reaching apex of florets (1); thinner than fertile lemma (8), or similar to fertile lemma in texture (9). Lower glume lanceolate (6), or oblong (8), or ovate (3); 0.25–0.8888–1.2 length of upper glume; membranous; 1-keeled; 1 -veined, or 2–7 -veined (1). Lower glume lateral veins absent (16), or distinct (1). Lower glume surface without pits. Lower glume apex emarginate (2), or obtuse (6), or acute (14), or acuminate (3); muticous (7), or mucronate (10). Upper glume lanceolate (6), or oblong (8), or ovate (3); 0.5–1.026–2 length of adjacent fertile lemma; membranous; 1-keeled; 1 -veined, or 2–7 -veined (1). Upper glume apex emarginate (1), or obtuse (7), or acute (13), or acuminate (3); muticous (14), or mucronate (3).

FLORETS Fertile lemma lanceolate (3), or elliptic (11), or oblong (2), or ovate (2); membranous (9), or chartaceous (8); without keel; wingless; 3 -veined. Lemma midvein eciliate (1), or ciliate (4), or pubescent (12). Lemma lateral veins obscure (1/1); excurrent (13), or extending close to apex (6). Lemma surface unwrinkled; without grooves. Lemma margins eciliate (1), or ciliate (6), or pubescent (10). Lemma apex entire (5), or dentate (14); 2 -fid (13/14), or 3 -fid (1/14); emarginate (5/6), or obtuse (5/6); muticous (2), or mucronate (14), or awned (2); 1 -awned (1/2), or 3 -awned (1/2). Principal lemma awn apical (15/16), or from a sinus (1/16). Palea 0.6–0.8617–1 length of lemma; 2 -veined (1/1). Palea keels smooth (14), or scaberulous (1), or scabrous (2), or tuberculate (1); eciliate (15), or pubescent (1), or ciliolate (1). Palea surface glabrous (16), or pubescent (1). Palea apex dentate (2/2). Apical sterile florets resembling fertile though underdeveloped.

FLOWER Lodicules 2 (1/1); fleshy (1/1). Anthers 3 (5/5).

FRUIT Caryopsis with adherent pericarp; lanceolate (1/12), or ellipsoid (4/12), or oblong (6/12), or ovoid (1/12), or obovoid (1/12); dorsally compressed (4/4); plano-convex (1/2), or concavo-convex (1/2); reticulate (2/2). Embryo 0.4–0.425–0.5 length of caryopsis. Hilum punctiform (4/5), or elliptic (1/5).

DISTRIBUTION Africa (1), or North America (11), or South America (6).

Please cite this publication as detailed in How to Cite Version: 27th January 2014.