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.

Arthrostylidium

HABIT Perennial. Rhizomes short; pachymorph. Culms erect (2/29), or geniculately ascending (1/29), or rambling (1/29), or arching (2/29), or leaning (4/29), or scandent (23/29); slender (16/16); 30–582.1–1560 cm long; woody; rooting from lower nodes (1/1). Culm-internodes unequal, the lower longer (1/1); terete. Culm-nodes swollen (1/1). Lateral branches fastigiate (9), or dendroid (23). Branch complement one (5/31), or two (5/31), or three (5/31), or several (12/31), or many (13/31); solitary (3/31), or in a clump (29/31); at the node (1), or subtended by a bare patch above the node (31); with subequal branches (13/26), or 1 branch dominant (13/26), or 2 branches dominant (1/26); thinner than stem (15/15). Culm-sheaths persistent (5/8), or tardily deciduous (1/8), or deciduous (2/8); without auricles (5/5). Culm-sheath blade linear (1/11), or lanceolate (8/11), or ovate (1/11), or triangular (1/11); constricted at base (1/1). Leaf-sheath auricles absent (29), or erect (3). Ligule an eciliate membrane (16), or a ciliolate membrane (16). Leaf-blade base with a brief petiole-like connection to sheath. Leaf-blades persistent (14), or deciduous at the ligule (18); filiform (1), or linear (1), or lanceolate (26), or oblong (1), or ovate (5); stiff (3), or firm (29). Leaf-blade midrib indistinct (5/5). Leaf-blade venation without cross veins (29), or with distinct cross veins (3).

INFLORESCENCE Inflorescence a panicle (1), or composed of racemes (31); terminal (18), or terminal and axillary (14).

Panicle contracted (1/1).

Racemes single (29/31), or borne along a central axis (2/31); bilateral (31/31); bearing few fertile spikelets (7/31), or many spikelets (24/31); bearing 1–8–25 fertile spikelets on each. Rhachis semiterete (5/5). Spikelet packing broadside to rhachis (18/18); contiguous (8/31), or lax (12/31), or distant (11/31); 2 -rowed (1/1).

Spikelets appressed (12/17), or ascending (3/17), or spreading (1/17), or pectinate (1/17), or deflexed (1/17); solitary (30), or in pairs (1), or clustered at each node (1). Fertile spikelets sessile, or sessile and pedicelled (1).

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets (18/20), or 2 basal sterile florets (2/20); 1–5–15 fertile florets; without rhachilla extension (1), or with diminished florets at the apex (31). Spikelets linear (24), or lanceolate (7), or obovate (1); laterally compressed (30), or subterete (2); 5–24.86–100 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes brief up to lowest fertile floret (31), or elongated between glumes (1); definite; glabrous (27), or sparsely hairy (1), or pubescent (2), or pilose (2). Floret callus pilose (1/1).

GLUMES Glumes one the lower absent or obscure (1), or two (30), or several (3); persistent; shorter than spikelet; thinner than fertile lemma (1), or similar to fertile lemma in texture. Lower glume lanceolate (12/31), or elliptic (5/31), or oblong (1/31), or ovate (13/31); 0.6–1.21–9 length of upper glume; membranous (1/31), or chartaceous (30/31); without keels (29/31), or 1-keeled (2/31); 1–2 -veined (5/16), or 3 -veined (13/16), or 4–5 -veined (6/16), or 6 -veined (1/16), or 7 -veined (2/16). Lower glume lateral veins absent (5/31), or obscure (2/31), or distinct (28/31), or prominent (1/31). Lower glume surface without pits (31/31); glabrous (26/31), or puberulous (3/31), or pubescent (2/31), or hispid (1/31). Lower glume apex obtuse (4/31), or acute (21/31), or acuminate (6/31). Upper glume lanceolate (21), or elliptic (4), or ovate (7); 0.33–0.7083–2 length of adjacent fertile lemma; membranous (1/4), or chartaceous (3/4); without keels (15/20), or 1-keeled (5/20), or 2-keeled (1/20); 3–4 -veined (5/18), or 5 -veined (11/18), or 6 -veined (6/18), or 7 -veined (11/18), or 8–9 -veined (2/18). Upper glume lateral veins without cross-veins (1/1), or with cross-veins (1/1). Upper glume surface glabrous (27), or puberulous (3), or pubescent (2), or hispid (1). Upper glume apex obtuse (3), or acute (23), or acuminate (6); muticous (27), or mucronate (4), or awned (2); 1 -awned (2/2).

FLORETS Basal sterile florets barren (20/20); with palea (6/9), or without significant palea (5/9). Lemma of lower sterile floret lanceolate (1/4), or elliptic (1/4), or ovate (2/4); chartaceous (1/1); 3–7 -veined (1/2), or 9 -veined (1/2); obtuse (1/4), or acute (2/4), or acuminate (1/4); muticous (3/4), or mucronate (1/4), or awned (1/4). Fertile lemma lanceolate (22), or elliptic (4), or oblong (1), or ovate (18); membranous (1), or chartaceous (31), or coriaceous (1); without keel (29), or keeled (3); wingless; 1–8–15 -veined. Lemma lateral veins obscure (1/4), or prominent (3/4). Lemma surface unwrinkled (28), or rugulose (4); without grooves; glabrous (26), or puberulous (4), or pubescent (4), or hispidulous (1). Lemma margins eciliate (26), or ciliolate (5), or ciliate (1). Lemma apex obtuse (6), or acute (24), or acuminate (2); without ornament (31), or pubescent (1); muticous (11), or mucronate (17), or awned (5); 1 -awned (4/4). Palea 1–1.002–1.1 length of lemma; 2 -veined (2/4), or 3–4 -veined (1/4). Palea keels smooth (31), or scaberulous (1); eciliate (25), or ciliolate (7). Palea surface glabrous (26), or puberulous (5), or pubescent (1). Apical sterile florets resembling fertile though underdeveloped (25/31), or distinct from fertile (6/31); 1 in number (6/6); rudimentary (5/6), or lanceolate (1/6).

FLOWER Lodicules 3; membranous (2/2); glabrous (29), or ciliate (3). Anthers 3. Stigmas 2 (31/31). Ovary unappendaged (14), or umbonate (18); glabrous (1/2), or pubescent on apex (1/2).

FRUIT Caryopsis with adherent pericarp. Embryo 0.15 length of caryopsis. Hilum linear (1/1); 1 length of caryopsis.

DISTRIBUTION North America (1), or South America.

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