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, 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 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.
Taxonomy. Chloridoideae; main chloridoid assemblage.
Distribution, ecology, phytogeography. 1 species; India. On rocks.
Paleotropical. Indomalesian. Indian.
References, etc. Morphological/taxonomic: Bor 1957b. Leaf anatomical: Metcalfe 1960; this project.
Special comments. Tripogon pauperculus.
Illustrations. • Abaxial epidermis of leaf blade
Cite this publication as: Watson, L., and Dallwitz, M. J. (1992 onwards). ‘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.’ http://biodiversity.uno.edu/delta/. Version: 18th August 1999. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993 onwards, 1998), and Watson and Dallwitz (1994), and Watson, Dallwitz, and Johnston (1986) should also be cited (see References).
