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The grass genera of the world

L. Watson, T.D. Macfarlane, and M.J. Dallwitz

Indopoa Bor

From the Greek poa (grass, fodder) and geography.

Habit, vegetative morphology. Annual (sometimes epiphytic). Culms 10–16 cm high; herbaceous; unbranched above. Leaves non-auriculate. Leaf blades linear; narrow; 1–2 mm wide (to 12 cm long); not cordate, not sagittate; setaceous (involute); without abaxial multicellular glands; without cross venation; persistent. Ligule present; an unfringed membrane; not truncate.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets; presumed inbreeding; seemingly exposed-cleistogamous.

Inflorescence. Inflorescence determinate; without pseudospikelets; a single spike (to 8 cm long); without capillary branchlets; non-digitate; espatheate (but the upper culm leaves sometimes reduced); not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; not secund (alternate).

Female-fertile spikelets. Spikelets morphologically ‘conventional’ (but seemingly cleistogamous); 7–9 mm long; adaxial; compressed laterally; disarticulating above the glumes; disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets. Hairy callus present. Callus pointed.

Glumes two; relatively large; very unequal; (the upper) long relative to the adjacent lemmas; free; dorsiventral to the rachis; hairless (glabrous, the nerves and mucro scaberulous); pointed; shortly awned, or awnless (but then mucronate); carinate; similar (thin, the G1 shorter and asymmetric at the tip). Lower glume 1 nerved. Upper glume 1 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped.

Female-fertile florets 4–6. Lemmas similar in texture to the glumes to decidedly firmer than the glumes; not becoming indurated; incised; 2 lobed; deeply cleft; awned. Awns 3; median and lateral; the median different in form from the laterals; from a sinus; geniculate (the base twisting); hairless (scabrid); much longer than the body of the lemma; entered by one vein. The lateral awns shorter than the median. Lemmas hairless; without a germination flap; 3 nerved (the median very broad, later curving round so as almost to longitudinally enclose the slender caryopsis); with the nerves non-confluent (extending into the 3 awns). Palea present; conspicuous but relatively short (about 4 mm long, compared with the 6 mm lemma); entire (oblanceolate); awnless, without apical setae; not indurated; 2-nerved; 2-keeled (the keels very shortly ciliate). Lodicules present; 2; free; glabrous. Stamens 3. Anthers minute, 0.25–0.3 mm long; not penicillate; without an apically prolonged connective. Ovary apically glabrous; with a conspicuous apical appendage (this glabrous, emarginate, fleshy). Stigmas 2; white.

Fruit, embryo and seedling. Fruit small to medium sized (3–4.5 mm long, very slender and needlelike, with an apical, glabrous, emarginate, fleshy appendage); linear (needle-like). Hilum short. Embryo small (about one-fifth of grain length). Seed endospermic. Endosperm hard (of a peculiar, flinty texture).

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally (the costals more regularly rectangular, and much narrower). Mid-intercostal long-cells rectangular and fusiform; having markedly sinuous walls and having straight or only gently undulating walls. Microhairs present; more or less spherical; clearly two-celled; chloridoid-type (of the sunken type). Microhair apical cell wall of similar thickness/rigidity to that of the basal cell. Microhairs 15–18 microns long. Microhair basal cells 6 microns long. Microhairs 9–12 microns wide at the septum. Microhair total length/width at septum 1.3–1.9. Microhair apical cell/total length ratio 0.76. Stomata common; 36–43.5 microns long. Subsidiaries low dome-shaped, or triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells absent or very rare. Intercostal silica bodies absent. Costal short-cells conspicuously in long rows. Costal silica bodies present in alternate cell files of the costal zones; saddle shaped (almost exclusively), or oryzoid (some tending to this).

Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section open.

C4; XyMS+. PCR sheaths of the primary vascular bundles interrupted; interrupted both abaxially and adaxially. PCR sheath extensions absent. Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups (between the vascular bundles, more conspicuous nearer the middle of the blade); in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’ (with the primaries). Sclerenchyma all associated with vascular bundles.

Classification. Watson & Dallwitz (1994): Chloridoideae; main chloridoid assemblage. Soreng et al. (2015): Chloridoideae. 1 species (I. paupercula).

Distribution, phytogeography, ecology. India.

On rocks.

References, etc. Morphological/taxonomic: Bor 1957b. Leaf anatomical: Metcalfe 1960, and studied by us.

Special comments. I. paupercula. Illustrations. • I. paupercula (as Tripogon pauperulus: Hook. Ic. Pl. 25 (1896). • I. paupercula, abaxial epidermis of leaf blade: this project

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, and classifications. See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., Macfarlane, T.D., and Dallwitz, M.J. 1992 onwards. The grass genera of the world: descriptions, illustrations, identification, and information retrieval; including synonyms, morphology, anatomy, physiology, phytochemistry, cytology, classification, pathogens, world and local distribution, and references. Version: 11th December 2017.’.