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The grass genera of the world

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

Decaryella A. Camus

Habit, vegetative morphology. Annual. Culms 10–30 cm high; herbaceous. Culm nodes glabrous. Leaves not basally aggregated; non-auriculate. Leaf blades narrow; flat, or rolled; not pseudopetiolate; without cross venation. Ligule a fringed membrane.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality.

Inflorescence. Inflorescence determinate; a single raceme (loose, narrow, 4–12 cm long); espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; not secund; long pedicellate; not in distinct ‘long-and-short’ combinations.

Female-fertile spikelets. Spikelets about 4.5 mm long; compressed dorsiventrally; falling with the glumes (and with the pedicels). Rachilla prolonged beyond the uppermost female-fertile floret, or terminated by a female-fertile floret (?); the rachilla extension when present, with incomplete florets, or naked. Hairy callus present (comprising the long, hairy pedicel). Callus long; pointed.

Glumes two; more or less equal; long relative to the adjacent lemmas; hairy; pointed; awned (both having a terminal, subulate awn 3–7 mm long); non-carinate (dorsally rounded); similar (thick, leathery, smooth). Lower glume 5 nerved. Upper glume 5 nerved. Spikelets with female-fertile florets only, or with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped. Spikelets without proximal incomplete florets.

Female-fertile florets 1–2. Lemmas less firm than the glumes (very thin); not becoming indurated; entire; pointed, or blunt; awnless; hairless; glabrous; non-carinate; 1 nerved, or 3 nerved. Palea present; entire; awnless, without apical setae; 2-nerved; 2-keeled.

Fruit, embryo and seedling. Embryo large.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Microhairs present; chloridoid-type. Stomata common. Subsidiaries dome-shaped and triangular. Intercostal short-cells common; in cork/silica-cell pairs. Prickles and macrohairs present. Costal short-cells conspicuously in long rows. Costal silica bodies ‘panicoid-type’; dumb-bell shaped.

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

C4; XyMS+. Mesophyll with radiate chlorenchyma. Bulliforms present in discrete, regular adaxial groups; associated with colourless mesophyll cells to form deeply-penetrating fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present. Sclerenchyma all associated with vascular bundles.

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

Distribution, phytogeography, ecology. Madagascar.

Species of open habitats. Dry bush.

Special comments. Spikelet description fairly inadequate. Fruit data wanting.


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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: 13th November 2017. delta-intkey.com/grass’.

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