Centrochloa Swallen
Habit, vegetative morphology. Annual; caespitose. Culms about 20–75 cm high; herbaceous; unbranched above. Culm nodes glabrous. Leaves mostly basal; non-auriculate. Leaf blades narrow; without cross venation; persistent; a fringed membrane.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence of spicate main branches (the rachides filiform); digitate to subdigitate. Rachides hollowed. Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes with very slender rachides; persistent. Spikelets solitary; secund.
Female-fertile spikelets. Spikelets 3 mm long; turbinate; adaxial; compressed dorsiventrally; falling with the glumes. Rachilla terminated by a female-fertile floret. Hairy callus present (as a downward-pointing hairy projection, perhaps representing the lower glume, at the base of the spikelet - cf. Digitariopsis).
Glumes one per spikelet (the upper); long relative to the adjacent lemmas; dorsiventral to the rachis; hairy (densely straight-hairy, with dark brown hairs in 4 rows between and outside the veins, and with the rows terminating apically in tufts); pointed; awnless; non-carinate. Upper glume 3 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. The proximal incomplete florets 1; sterile. The proximal lemmas awnless; 2–3 nerved; more or less equalling the female-fertile lemmas; less firm than the female-fertile lemmas; not becoming indurated.
Female-fertile florets 1. Lemmas decidedly firmer than the glumes (cartilaginous); not becoming indurated; entire; pointed; awnless; hairless; non-carinate; having the margins lying flat on the palea; with a clear germination flap; 5 nerved. Palea present; relatively long; 2-nerved; keel-less. Lodicules present; 2; free; fleshy; glabrous; not or scarcely vascularized. Stamens 3. Ovary glabrous. Stigmas 2.
Fruit, embryo and seedling. Fruit small; compressed dorsiventrally. Hilum short. Embryo large.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally (the intercostals short and broad, the costals long and narrow); of similar wall thickness costally and intercostally (fairly thin walled). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; panicoid-type. Stomata common. Subsidiaries triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells absent or very rare. Costal short-cells conspicuously in long rows. Costal silica bodies ‘panicoid-type’.
Transverse section of leaf blade, physiology. C4; XyMS–. Mesophyll with radiate chlorenchyma. Leaf blade adaxially flat. Midrib conspicuous; having a conventional arc of bundles; with colourless mesophyll adaxially. Bulliforms not present in discrete, regular adaxial groups (constituting most of the epidermis). Many of the smallest vascular bundles unaccompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’. Sclerenchyma all associated with vascular bundles.
Special diagnostic feature. Upper glume extended downwards into a conspicuous spur.
Taxonomy. Panicoideae; Panicodae; Paniceae.
Distribution, ecology, phytogeography. 1 species; Brazil. Species of open habitats. Savanna.
Neotropical. Central Brazilian.
References, etc. Leaf anatomical: this project.
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).