| # 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. The shoots not aromatic. Leaves not basally aggregated; clearly differentiated into sheath and blade; non-auriculate. Leaf blades narrow; flat, or rolled; without cross venation. Ligule a fringed membrane.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.

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 (D. madagascariensis).

Distribution, phytogeography, ecology. Madagascar.

Species of open habitats. Dry bush.

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

Illustrations. • Decaryella madagascariensis: Vorontsova & Rakotoarisoa 2014).

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: 15th June 2025. delta-intkey.com’.

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