Merostachys

HABIT Perennial. Rhizomes absent (1), or short (44); pachymorph (44/44). Culms erect (25/34), or arching (3/34), or leaning (3/34), or scandent (4/34); 150–960.5–3000 cm long; woody. Culm-internodes terete. Culm-nodes flush with internodes (1/9), or swollen (8/9); without obvious supra-nodal ridge (1/4), or with distinct supra-nodal ridge (3/4). Lateral branches dendroid. Branch complement three (1/44), or several (3/44), or many (41/44); flabellate; with subequal branches (6/6); thinner than stem (21/21). 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 (41), or erect (3), or falcate (1). Ligule an eciliate membrane (2), or a ciliolate membrane (42), or absent (1). Leaf-blade base with a brief petiole-like connection to sheath. Leaf-blades linear (3), or lanceolate (36), or elliptic (1), or oblong (15), or ovate (11). Leaf-blade midrib indistinct (2/2). Leaf-blade venation without cross veins (39), or with obscure cross veins (1), or with distinct cross veins (5).

INFLORESCENCE Inflorescence composed of racemes (39/39); exserted (33/39), or embraced at base by subtending leaf (7/39). Peduncle cylindrical at apex (1/1), or tipped by a glumaceous appendage (1/1).

Racemes single (39/39); unilateral (39/39); bearing 1–17–32 fertile spikelets on each. Rhachis angular (15/15); terminating in a spikelet (1/39), or sterile spikelet (38/39). Spikelet packing broadside to rhachis (39/39); crowded (3/39), or contiguous (32/39), or lax (3/39), or distant (1/39); 2 -rowed (7/7).

Spikelets appressed (1/29), or spreading (3/29), or pectinate (24/29), or deflexed (2/29); solitary (34/37), or in pairs (4/37), or in threes (1/37). Fertile spikelets sessile (13/39), or pedicelled (26/39); 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 (25/26), or fused to each other (1/26); oblong (9/9).

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets (9/10), or 2 basal sterile florets (1/10); 1 fertile florets (36/39), or 2 fertile florets (5/39), or 3–4 fertile florets (1/39), or 5 fertile florets (2/39), or 6–10 fertile florets (1/39); with a barren rhachilla extension (20/39), or with diminished florets at the apex (21/39). Spikelets lanceolate (13/39), or elliptic (23/39), or oblong (1/39), or ovate (2/39), or cuneate (1/39); laterally compressed (39/39); 4–13.93–55 mm long; breaking up at maturity (39/39); disarticulating below each fertile floret (39/39). Rhachilla internodes brief up to lowest fertile floret (38/39), or elongated below proximal fertile floret (1/39); definite (7/7); glabrous (6/7), or pubescent (1/7). Floret callus pubescent (1/1).

GLUMES Glumes one the lower absent or obscure (9/39), or two (31/39); persistent (39/39); shorter than spikelet (34/39), or reaching apex of florets (4/39), or exceeding apex of florets (1/39). Lower glume linear (3/31), or lanceolate (15/31), or elliptic (3/31), or ovate (11/31); clasping (1/1); 0.25–0.386–0.5 length of upper glume; membranous (10/26), or chartaceous (16/26); without keels (9/22), or 1-keeled (13/22); 0 -veined (1/25), or 1 -veined (21/25), or 3 -veined (1/25), or 5 -veined (1/25), or 9–11 -veined (1/25). Lower glume lateral veins absent (21/31), or distinct (9/31), or prominent (1/31). Lower glume surface without pits (31/31); glabrous (17/31), or puberulous (11/31), or pubescent (3/31). Lower glume apex acute (12/29), or acuminate (14/29), or attenuate (2/29), or setaceously attenuate (2/29); muticous (29/31), or mucronate (1/31), or awned (1/31). Upper glume lanceolate (12/39), or elliptic (5/39), or oblong (1/39), or ovate (20/39), or orbicular (1/39); 0.01–0.655–1 length of adjacent fertile lemma; membranous (13/39), or chartaceous (26/39); without keels (4/9), or 1-keeled (5/9); 0–9–17 -veined. Upper glume primary vein eciliate (37/38), or pubescent (1/38). Upper glume lateral veins without ribs (35/36), or ribbed (1/36); transversely connected at apex (3/6), or with cross-veins (3/6). Upper glume surface smooth (33/39), or asperulous (3/39), or scabrous (3/39); glabrous (25/39), or puberulous (9/39), or pubescent (4/39), or hispid (1/39). Upper glume apex obtuse (1/38), or acute (19/38), or acuminate (14/38), or attenuate (2/38), or setaceously attenuate (1/38), or caudate (1/38); muticous (27/39), or mucronate (4/39), or awned (8/39); 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 (1/39), or lanceolate (13/39), or elliptic (3/39), or oblong (5/39), or ovate (21/39); chartaceous (33/39), or cartilaginous (1/39), or coriaceous (5/39); without keel (37/39), or keeled (2/39); wingless (39/39); 5–14–23 -veined. Lemma lateral veins obscure (1/1). Lemma surface smooth (34/39), or granulose (1/39), or scaberulous (4/39); unwrinkled (39/39); without grooves (39/39); glabrous (13/39), or puberulous (13/39), or pubescent (13/39), or pilose (1/39). Lemma margins eciliate (26/39), or ciliolate (3/39), or ciliate (8/39), or pubescent (1/39), or woolly (1/39). Lemma apex acute (26/31), or acuminate (5/31); muticous (35/39), or mucronate (3/39), or awned (1/39); 1 -awned (1/1). Palea 1–1.004–1.1 length of lemma; membranous (12/39), or chartaceous (24/39), or cartilaginous (1/39), or coriaceous (2/39); 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 (14/39), or approximate (1/39), or contiguous above a sulcus (24/39); smooth (37/39), or scaberulous (2/39); eciliate (25/39), or ciliolate (12/39), or ciliate (1/39), or woolly (1/39). Palea surface glabrous (32/39), or puberulous (4/39), or pilose (2/39), or woolly (1/39). Palea apex muticous (38/39), or with excurrent keel veins (1/39). Apical sterile florets resembling fertile though underdeveloped (1/21), or distinct from fertile (20/21); 1 in number (20/20); rudimentary (19/20), or linear (1/20).

FLOWER Lodicules 3 (39/39); glabrous (31/39), or ciliate (8/39). Anthers 3 (39/39). Stigmas 2 (38/39), or 3 (1/39). 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: 16th November 2012.