Ischaemum L.

Gramineae, T. A. Cope. Flora Zambesiaca 10:4. 2002

Habit

Perennials, sometimes annuals, often decumbent.

Leaf sheaths

Leaf sheaths mostly with auricles; ligule membranous; leaf laminas linear, sometimes sagittate or falsely petiolate at the base.

Inflorescences

Inflorescence of paired, sometimes solitary or digitate, 1-sided racemes, those of a pair often interlocked back to back and mimicking a solitary raceme, terminal or axillary; rhachis internodes and pedicels stoutly linear to clavate or inflated, often exposed on the back of the raceme as a U- or V-shaped segment, sometimes the pedicels so short that the spikelets of a pair appear to be side by side.

Spikelets

Sessile spikelet dorsally compressed; callus obtuse and inserted in the concave top of the internode; inferior glume chartaceous to coriaceous, convex to concave on the back, laterally 2-keeled, often rugose, sometimes winged; superior glume awned or awnless; inferior floret male, rarely barren, with a palea; superior lemma bifid, passing between the teeth into a glabrous awn (rarely awnless). Pedicelled spikelet as large as the sessile spikelet or much smaller, often asymmetrical.

Fruits

Caryopsis oblong to lanceolate, dorsally compressed.

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Habit

Annual (28), or perennial (52). Rhizomes absent (74), or short (4), or elongated (2). Stolons absent (75), or present (5). Culms erect (27/66), or geniculately ascending (19/66), or decumbent (26/66), or prostrate (9/66), or rambling (9/66); robust (2/8), or slender (4/8), or weak (2/8); 5-63.92-300 cm long; firm (76), or wiry (3), or woody (1); without nodal roots (2/27), or with prop roots (2/27), or rooting from lower nodes (25/27). Culm-internodes terete (2/3), or channelled (2/3). Culm-nodes constricted (1/2), or swollen (1/2). Lateral branches lacking (10/27), or sparse (7/27), or ample (14/27). Leaf-sheath auricles absent (72), or erect (8). Ligule an eciliate membrane (68), or a ciliolate membrane (12), or a fringe of hairs (1). Leaf-blade base without a false petiole (63), or with a brief petiole-like connection to sheath (5), or with a false petiole (17). Leaf-blades linear (47), or lanceolate (44), or elliptic (4), or oblong (3), or ovate (2); herbaceous (79), or coriaceous (1); stiff (1), or firm (77), or flaccid (2). Leaf-blade margins cartilaginous (1/1).

Inflorescences

Inflorescence composed of racemes; terminal (76), or terminal and axillary (4); subtended by an unspecialized leaf-sheath (71), or an inflated leaf-sheath (2), or a spatheole (7); exserted (78), or embraced at base by subtending leaf (2), or enclosed (3). Spatheole lanceolate (5/5). Racemes single (8), or paired (71), or digitate (10); side by side (31/75), or appressed back to back (44/75); unilateral (2/2); bearing 8-9 fertile spikelets on each (1/2), or 10-12 fertile spikelets on each (2/2), or 13-14 fertile spikelets on each (1/2). Rhachis fragile at the nodes; angular (68/76), or subterete (4/76), or semiterete (4/76). Rhachis internodes linear (5), or columnar (9), or oblong (35), or clavate (15), or cuneate (8), or pyriform (1), or inflated (7); unspecialized (23), or flat and forming a U or V shape with the pedicel in rear view (56), or with a basal circular pore between internode and pedicel (4), or with the lower often bearing triads (2). Rhachis internode tip transverse (79), or oblique (1); cupuliform (79), or notched (1). Spikelets in pairs. Fertile spikelets sessile (78), or sessile and pedicelled (3); 1 in the cluster (78), or 2 in the cluster (3). Companion sterile spikelets pedicelled (78/78); 0 in the cluster (1/78), or 1 in the cluster (78/78). Pedicels linear (5/79), or columnar (9/79), or oblong (48/79), or narrowly elliptic (1/79), or clavate (8/79), or cuneate (6/79), or pyriform (1/79), or inflated (1/79).

Sterile

Basal sterile spikelets absent (78), or well-developed (2). Companion sterile spikelets absent (2), or represented by single glumes (2), or rudimentary (6), or well-developed (76); persistent (2/76), or separately deciduous (76/76). Companion sterile spikelet callus indistinct (77/78), or oblong (1/78). Companion sterile spikelet glumes muticous (36/47), or mucronate (1/47), or awned (10/47).

Spikelets

Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets linear (1), or lanceolate (19), or elliptic (21), or oblong (39), or ovate (13), or obovate (2), or rhomboid (1); laterally compressed (1), or dorsally compressed (79); 2.5-6.055-12 mm long; falling entire; deciduous from the base (2), or with accessory branch structures. Spikelet callus brief (39), or square (11), or oblong (27), or cuneate (3); glabrous (9/58), or pubescent (18/58), or pilose (21/58), or bearded (13/58); base truncate (65), or obtuse (15); inserted. Basal sterile spikelets absent (78), or well-developed (2). Companion sterile spikelets absent (2), or represented by single glumes (2), or rudimentary (6), or well-developed (76); persistent (2/76), or separately deciduous (76/76). Companion sterile spikelet callus indistinct (77/78), or oblong (1/78). Companion sterile spikelet glumes muticous (36/47), or mucronate (1/47), or awned (10/47).

Fertile

Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets linear (1), or lanceolate (19), or elliptic (21), or oblong (39), or ovate (13), or obovate (2), or rhomboid (1); laterally compressed (1), or dorsally compressed (79); 2.5-6.055-12 mm long; falling entire; deciduous from the base (2), or with accessory branch structures. Spikelet callus brief (39), or square (11), or oblong (27), or cuneate (3); glabrous (9/58), or pubescent (18/58), or pilose (21/58), or bearded (13/58); base truncate (65), or obtuse (15); inserted.

Glume

Glumes reaching apex of florets (2), or exceeding apex of florets (78); firmer than fertile lemma. Lower glume subulate (1), or lanceolate (11), or elliptic (14), or oblong (46), or ovate (20), or obovate (1); membranous (1), or chartaceous (12), or cartilaginous (1), or coriaceous (66), or indurate (1); without keels (1), or 2-keeled (79); wingless (44), or winged on keel (38); 1-9-21 -veined. Lower glume lateral veins obscure (6), or distinct (74); intercarinal veins distinct (1/1). Lower glume surface convex (48), or flat (33), or concave (2); smooth (46), or asperulous (6), or scabrous (3), or muricate (11), or rugose (20); not waisted (77), or laterally waisted (3); glabrous (60), or puberulous (1), or pubescent (6), or pilose (15), or hirsute (3), or villous (9), or woolly (1); without hair tufts (78), or with marginal tufts of hair (1), or with transverse tufts of hair (1). Lower glume apex entire (49), or erose (1), or dentate (31); 2 -fid (28/31), or 3 -fid (3/31); emarginate (5/34), or truncate (1/34), or obtuse (8/34), or acute (20/34), or acuminate (3/34), or attenuate (1/34); muticous (74), or mucronate (1), or awned (6). Upper glume lanceolate (62), or elliptic (6), or oblong (3), or ovate (14); membranous (1), or chartaceous (19), or cartilaginous (1), or coriaceous (60); with undifferentiated margins (78), or hyaline margins (1), or membranous margins (1); without keels (1), or 1-keeled (79); wingless (58), or winged on keel (22); 1 -veined (1/49), or 3 -veined (25/49), or 4 -veined (9/49), or 5 -veined (25/49), or 6 -veined (2/49), or 7 -veined (7/49), or 8-9 -veined (2/49). Upper glume primary vein eciliate (73), or ciliolate (1), or ciliate (6). Upper glume lateral veins with cross-veins (1/1). Upper glume surface smooth (68), or asperulous (4), or scabrous (6), or tuberculate (1), or rugose (1); glabrous (68), or puberulous (2), or pubescent (3), or pilose (4), or hirsute (1), or villous (2); without hair tufts (77), or with marginal tufts of hair (1), or with a dorsal tuft of hair (2). Upper glume apex entire (76), or dentate (3), or lobed (1); 2 -fid (4/4); emarginate (2/35), or obtuse (4/35), or acute (8/35), or acuminate (21/35), or attenuate (2/35), or setaceously attenuate (1/35); muticous (58), or mucronate (5), or awned (19); 1 -awned (17/18), or 2 -awned (1/18).

Florets

Basal sterile florets male (78), or barren (2); with palea (79), or without significant palea (1). Lemma of lower sterile floret lanceolate (57), or elliptic (9), or oblong (16), or ovate (11); hyaline (27), or membranous (53); 1-2 -veined (4/50), or 3 -veined (43/50), or 4 -veined (11/50), or 5 -veined (12/50), or 7 -veined (2/50); truncate (2/25), or obtuse (1/25), or acute (14/25), or acuminate (9/25). Palea of lower sterile floret wingless (78/79), or winged on keels (1/79). Fertile lemma linear (1), or lanceolate (8), or elliptic (4), or oblong (64), or ovate (3); hyaline (21), or membranous (59); without keel; wingless (79), or winged on margins (1); 1 -veined (2/39), or 3 -veined (34/39), or 4 -veined (3/39), or 5 -veined (6/39). Lemma lateral veins obscure (4/4). Lemma margins eciliate (60), or ciliolate (9), or ciliate (11). Lemma apex entire (3), or dentate (13), or lobed (67); 2 -fid (79/79); incised 0.1-0.471-0.75 of lemma length; muticous (8), or mucronate (3), or awned (75), or awned only on distal spikelets (1); 1 -awned (76/76). Principal lemma awn apical (3/78), or from a sinus (76/78); straight (6/78), or curved (3/78), or flexuous (1/78), or geniculate (70/78). Palea present (79), or absent or minute (1); 0.33-0.9752-1 length of lemma; hyaline (4/79), or membranous (75/79); 0 -veined (1/4), or 2 -veined (3/4); without keels (1/79), or 2-keeled (78/79). Palea keels smooth (77/78), or scaberulous (1/78).

Flowers

Lodicules 2 (14/14); free (13/14), or adnate to palea (1/14). Anthers 3 (70/70).

Fruits

Caryopsis with adherent pericarp (5/5); ellipsoid (2/5), or oblong (3/5), or obovoid (1/5); dorsally compressed (1/1).

Distribution

Africa (12), or Temperate Asia (14), or Tropical Asia (65), or Australasia (9), or Pacific (10), or North America (2), or South America (7).