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.

Merostachys

HABIT Perennial. Rhizomes absent (1), or short (45); pachymorph (45/45). Culms erect (26/35), or arching (3/35), or leaning (3/35), or scandent (4/35); 150–968.7–3000 cm long; woody. Culm-internodes terete. Culm-nodes flush with internodes (1/10), or swollen (9/10); without obvious supra-nodal ridge (1/4), or with distinct supra-nodal ridge (3/4). Lateral branches dendroid. Branch complement three (1/45), or several (3/45), or many (42/45); flabellate; with subequal branches (6/6); thinner than stem (22/22). Culm-sheaths tardily deciduous (1/27), or deciduous but leaving a persistent girdle (1/27), or deciduous (25/27); auriculate (3/3). Culm-sheath blade linear (4/21), or lanceolate (17/21); constricted at base (1/1). Leaf-sheath auricles absent (42), or erect (3), or falcate (1). Ligule an eciliate membrane (2), or a ciliolate membrane (43), or absent (1). Leaf-blade base with a brief petiole-like connection to sheath. Leaf-blades linear (3), or lanceolate (37), or elliptic (1), or oblong (16), or ovate (11). Leaf-blade midrib indistinct (2/2). Leaf-blade venation without cross veins (40), or with obscure cross veins (1), or with distinct cross veins (5).

INFLORESCENCE Inflorescence composed of racemes (40/40); exserted (34/40), or embraced at base by subtending leaf (7/40). Peduncle cylindrical at apex (1/1), or tipped by a glumaceous appendage (1/1).

Racemes single (40/40); unilateral (40/40); bearing 1–19–40 fertile spikelets on each. Rhachis angular (15/15); terminating in a spikelet (1/40), or sterile spikelet (39/40). Spikelet packing broadside to rhachis (40/40); crowded (3/40), or contiguous (33/40), or lax (3/40), or distant (1/40); 2 -rowed (7/7).

Spikelets appressed (1/30), or spreading (3/30), or pectinate (25/30), or deflexed (2/30); solitary (35/38), or in pairs (4/38), or in threes (1/38). Fertile spikelets sessile (13/40), or pedicelled (27/40); 1 in the cluster (1/2), or 2 in the cluster (2/2), or 3 in the cluster (1/2); the upper smaller (1/1). Pedicels free (26/27), or fused to each other (1/27); oblong (9/9).

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets (9/10), or 2 basal sterile florets (1/10); 1 fertile florets (37/40), or 2 fertile florets (5/40), or 3–4 fertile florets (1/40), or 5 fertile florets (2/40), or 6–10 fertile florets (1/40); with a barren rhachilla extension (20/40), or with diminished florets at the apex (22/40). Spikelets lanceolate (13/40), or elliptic (24/40), or oblong (1/40), or ovate (2/40), or cuneate (1/40); laterally compressed (40/40); 4–13.94–55 mm long; breaking up at maturity (40/40); disarticulating below each fertile floret (40/40). Rhachilla internodes brief up to lowest fertile floret (39/40), or elongated below proximal fertile floret (1/40); definite (7/7); glabrous (6/7), or pubescent (1/7). Floret callus pubescent (1/1).

GLUMES Glumes one the lower absent or obscure (9/40), or two (32/40); persistent (40/40); shorter than spikelet (35/40), or reaching apex of florets (4/40), or exceeding apex of florets (1/40). Lower glume linear (3/32), or lanceolate (15/32), or elliptic (3/32), or ovate (12/32); clasping (1/1); 0.25–0.3883–0.5 length of upper glume; membranous (10/27), or chartaceous (17/27); without keels (9/22), or 1-keeled (13/22); 0 -veined (1/26), or 1 -veined (22/26), or 3 -veined (1/26), or 5 -veined (1/26), or 9–11 -veined (1/26). Lower glume lateral veins absent (22/32), or distinct (9/32), or prominent (1/32). Lower glume surface without pits (32/32); glabrous (18/32), or puberulous (11/32), or pubescent (3/32). Lower glume apex acute (13/30), or acuminate (14/30), or attenuate (2/30), or setaceously attenuate (2/30); muticous (29/32), or mucronate (2/32), or awned (1/32). Upper glume lanceolate (12/40), or elliptic (5/40), or oblong (1/40), or ovate (21/40), or orbicular (1/40); 0.01–0.6656–1 length of adjacent fertile lemma; membranous (13/40), or chartaceous (27/40); without keels (4/9), or 1-keeled (5/9); 0–9–17 -veined. Upper glume primary vein eciliate (38/39), or pubescent (1/39). Upper glume lateral veins without ribs (36/37), or ribbed (1/37); transversely connected at apex (3/6), or with cross-veins (3/6). Upper glume surface smooth (34/40), or asperulous (3/40), or scabrous (3/40); glabrous (26/40), or puberulous (9/40), or pubescent (4/40), or hispid (1/40). Upper glume apex obtuse (1/39), or acute (19/39), or acuminate (15/39), or attenuate (2/39), or setaceously attenuate (1/39), or caudate (1/39); muticous (27/40), or mucronate (5/40), or awned (8/40); 1 -awned (8/8).

FLORETS Basal sterile florets barren (10/10); without significant palea (10/10). Lemma of lower sterile floret elliptic (3/10), or oblong (1/10), or ovate (7/10); 0.5–0.75–1 length of fertile lemma; chartaceous (4/4); 5 -veined (1/5), or 7 -veined (3/5), or 15–17 -veined (1/5); without grooves (8/10), or sulcate (2/10); obtuse (2/9), or acute (5/9), or acuminate (2/9); muticous (7/10), or mucronate (3/10). Fertile lemma linear (1/40), or lanceolate (13/40), or elliptic (3/40), or oblong (5/40), or ovate (22/40); chartaceous (33/40), or cartilaginous (1/40), or coriaceous (6/40); without keel (38/40), or keeled (2/40); wingless (40/40); 5–14–23 -veined. Lemma lateral veins obscure (1/1). Lemma surface smooth (35/40), or granulose (1/40), or scaberulous (4/40); unwrinkled (40/40); without grooves (40/40); glabrous (14/40), or puberulous (13/40), or pubescent (13/40), or pilose (1/40). Lemma margins eciliate (27/40), or ciliolate (3/40), or ciliate (8/40), or pubescent (1/40), or woolly (1/40). Lemma apex acute (27/32), or acuminate (5/32); muticous (36/40), or mucronate (3/40), or awned (1/40); 1 -awned (1/1). Palea 1–1.004–1.1 length of lemma; membranous (12/40), or chartaceous (25/40), or cartilaginous (1/40), or coriaceous (2/40); 2 -veined (3/17), or 6 -veined (1/17), or 8 -veined (3/17), or 9 -veined (1/17), or 10 -veined (4/17), or 11 -veined (3/17), or 12 -veined (7/17), or 13–14 -veined (2/17). Palea keels separated (14/40), or approximate (1/40), or contiguous above a sulcus (25/40); smooth (37/40), or scaberulous (2/40), or scabrous (1/40); eciliate (26/40), or ciliolate (12/40), or ciliate (1/40), or woolly (1/40). Palea surface glabrous (33/40), or puberulous (4/40), or pilose (2/40), or woolly (1/40). Palea apex muticous (39/40), or with excurrent keel veins (1/40). Apical sterile florets resembling fertile though underdeveloped (1/22), or distinct from fertile (21/22); 1 in number (21/21); rudimentary (19/21), or linear (2/21).

FLOWER Lodicules 3 (40/40); membranous (1/1); glabrous (32/40), or ciliate (8/40). Anthers 3 (40/40). Stigmas 2 (39/40), or 3 (1/40). Ovary glabrous (1/1).

FRUIT Caryopsis with free brittle pericarp (35/35); ellipsoid (2/11), or oblong (3/11), or ovoid (6/11); smooth (2/3), or striate (1/3); apex unappendaged (1/3), or rostrate (2/3). Embryo 0.1 length of caryopsis. Hilum linear (2/2).

DISTRIBUTION South America.

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