| # The grass genera of the world |

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

### Microcalamus Franch.

Habit, vegetative morphology. Perennial; rhizomatous and stoloniferous. Culms 15–60 cm high; herbaceous; unbranched above. Culm nodes hairy. Young shoots extravaginal. Leaves not basally aggregated; non-auriculate. Leaf blades lanceolate to ovate; broad; 15–50 mm wide; pseudopetiolate; cross veined; persistent. Ligule present; an unfringed membrane, or a fringed membrane (laciniate, minutely fringed).

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

Inflorescence. Inflorescence paniculate; open, or contracted (about the primary branches); espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.

Female-fertile spikelets. Spikelets weakly compressed laterally; falling with the glumes. Rachilla terminated by a female-fertile floret. Hairy callus present.

Glumes two; very unequal; shorter than the adjacent lemmas; hairless; pointed; awnless; non-carinate; similar (ovate, papery). Lower glume 5–7 nerved. Upper glume 5–7 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. The proximal incomplete florets 1; paleate. Palea of the proximal incomplete florets fully developed. The proximal incomplete florets sterile. The proximal lemmas awnless; 7 nerved; somewhat exceeded by the female-fertile lemmas; less firm than the female-fertile lemmas (papery, similar to the glumes); not becoming indurated.

Female-fertile florets 1. Lemmas rostrate or subulate; similar in texture to the glumes to decidedly firmer than the glumes (subleathery); not becoming indurated; entire; pointed; crested at the tip; awnless (but beaked); hairy; non-carinate; having the margins lying flat on the palea; without a germination flap; 5 nerved. Palea present; relatively long; entire; 2-nerved; 2-keeled. Lodicules present; 2; free; fleshy; glabrous; not or scarcely vascularized. Stamens 3. Anthers not penicillate; without an apically prolonged connective. Ovary apically glabrous. Styles fused. Stigmas 2; white (in dried material).

Fruit, embryo and seedling. Hilum short.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Intercostal zones exhibiting many atypical long-cells. Mid-intercostal long-cells having straight or only gently undulating walls. Microhairs present; panicoid-type. Stomata common (but very localised, in one or two rows adjoining veins). Subsidiaries triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs; silicified. Costal short-cells conspicuously in long rows. Costal silica bodies ‘panicoid-type’; mostly cross shaped; not sharp-pointed.

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma. Leaf blade adaxially flat. Midrib conspicuous (keel, large bundle); with one bundle only. Bulliforms not present in discrete, regular adaxial groups (constituting most of epidermis). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (midrib bundle only); forming ‘figures’ (in the midrib). Sclerenchyma all associated with vascular bundles.

Classification. Watson & Dallwitz (1994): Panicoideae; Panicodae; Paniceae. Soreng et al. (2015): Panicoideae; Panicodae; Paniceae; Boivinellinae. 4 species.

Distribution, phytogeography, ecology. Tropical west Africa.

Shade species; glycophytic. In forest.

References, etc. Leaf anatomical: studied by us - M. barbinoides Franch.

Illustrations. • Microcalamus barbinodis, as M. convallarioides: Hook. Ic. Pl. 31 (1916). • Microcalamus barbinodis (as barbinoides: Camus 1913).

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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