Triniochloa A. Hitchc.
Habit, vegetative morphology. Perennial; caespitose. Culms herbaceous. Leaves non-auriculate. Sheath margins joined. Leaf blades without cross venation; an unfringed membrane; not truncate; 8–9 mm long.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate; open; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets 10–12 mm long; not noticeably compressed, or compressed dorsiventrally; disarticulating above the glumes. Rachilla terminated by a female-fertile floret. Hairy callus present. Callus blunt.
Glumes present; two; relatively large; very unequal; shorter than the spikelets, or about equalling the spikelets; shorter than the adjacent lemmas, or long relative to the adjacent lemmas; pointed (acute or acuminate); awnless; non-carinate; similar (thin, membranous, papery). Lower glume 1 nerved. Upper glume 1 nerved. Spikelets with female-fertile florets only; without proximal incomplete florets.
Female-fertile florets 1. Lemmas decidedly firmer than the glumes (subleathery); not becoming indurated; incised; setaceously 2 lobed; not deeply cleft; awned. Awns 1; median; dorsal; from near the top, or from well down the back; geniculate; entered by several veins. Lemmas hairless; non-carinate; without a germination flap; 5(–7) nerved. Palea present; relatively long; 2-nerved; closely 2-keeled (sulcate between). Lodicules present; 2; joined; fleshy; glabrous; not or scarcely vascularized. Stamens 3. Ovary glabrous. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit medium sized (about 5 mm long); compressed dorsiventrally. Hilum long-linear. Embryo small. Endosperm hard. Embryo with an epiblast.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular and fusiform; having markedly sinuous walls and having straight or only gently undulating walls. Microhairs absent. Stomata absent or very rare. Intercostal short-cells common; not paired (nearly all solitary); not silicified. A few prickles present over the veins. Costal zones with short-cells. Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies horizontally-elongated crenate/sinuous and ‘panicoid-type’ (a continuous series of elongated-crenate, elongated-nodular and crosses, even a few dumb-bells); when panicoid type, cross shaped, or dumb-bell shaped, or nodular; not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade. Leaf blade with the ribs very irregular in sizes. Midrib conspicuous (via its large bundle and a prominent abaxial keel); with one bundle only. The lamina symmetrical on either side of the midrib. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with all the bundles); forming ‘figures’ (the large bundles with T’s, the smaller bundles with I’s). Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 8. 2n = 32. 4 ploid.
Taxonomy. Pooideae; Poodae; Meliceae.
Distribution, ecology, phytogeography. 4–5 species; Mexico to Ecuador and Peru. Xerophytic; species of open habitats. Stony hillsides.
Neotropical. Caribbean and Andean.
References, etc. Leaf anatomical: this project.
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).
