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The grass genera of the world

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

Microbriza Parodi ex Nicora et Rúg.

~ Chascolytrum

Including Monostemon Henr.

Habit, vegetative morphology. Perennial; caespitose. Culms 40–80 cm high; herbaceous; unbranched above. Young shoots intravaginal. Leaves not basally aggregated; non-auriculate; without auricular setae. Sheaths glabrous or pilose, becoming fibrous when dead. Leaf blades linear; narrow; flat; not pseudopetiolate; without cross venation; persistent (the fibrous remains of the sheaths persisting). Ligule an unfringed membrane; truncate; 1–3 mm long.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets; exposed-cleistogamous, or chasmogamous.

Inflorescence. Inflorescence paniculate; open (the spikelets clustered at the extremities); with capillary branchlets; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate; imbricate.

Female-fertile spikelets. Spikelets 1.2–2.5 mm long; compressed laterally (the individual florets dorsiventrally compressed); disarticulating above the glumes; not disarticulating between the florets (at least, the florets tending to fall together); with conventional internode spacings. Rachilla prolonged beyond the uppermost female-fertile floret. Hairy callus absent.

Glumes two; more or less equal; about equalling the spikelets; long relative to the adjacent lemmas; hairless; scabrous (to echinulate); awnless; carinate to non-carinate; similar (broadly lanceolate-navicular). Lower glume 3 nerved. Upper glume 3 nerved. Spikelets with female-fertile florets only, or with incomplete florets (the presence of a distal rudiment variable). The incomplete florets (when present) distal to the female-fertile florets. The distal incomplete florets when present, merely underdeveloped; awnless.

Female-fertile florets 2–3. Lemmas navicular, dorsally gibbous but without the Briza umbo, the margins infolded on the palea; similar in texture to the glumes; not becoming indurated (leathery); entire; pointed to blunt; awnless to mucronate; hairless; verrucose to echinulate; non-carinate; without a germination flap; 5 nerved. Palea present; relatively long; tightly clasped by the lemma; entire (lanceolate, acute); awnless, without apical setae; textured like the lemma (leathery); not indurated; 2-nerved; 2-keeled (and flat between the keels). Palea keels wingless; glabrous to scabrous. Lodicules present; 2; free; membranous; glabrous; not toothed (lanceolate). Stamens 1. Ovary apically glabrous. Styles free to their bases. Stigmas 2.

Fruit, embryo and seedling. Fruit adhering to lemma and/or palea (adhering to the palea along the two lateral grooves); small; ellipsoid; with two lateral, longitudinal grooves, wherein lie the margins of the palea; compressed dorsiventrally (ventrally flattened, dorsally convex). Hilum short. Embryo small. Endosperm hard.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally (the costals much narrower, rectangular). Mid-intercostal long-cells fusiform; having straight or only gently undulating walls. Microhairs absent. Stomata fairly common. Subsidiaries parallel-sided. Guard-cells overlapped by the interstomatals. Intercostal short-cells absent or very rare. Costal short-cells conspicuously in long rows (the long rows interrupted only occasionally, by prickles). Costal silica bodies horizontally-elongated crenate/sinuous, or ‘panicoid-type’ (the bodies ill defined, in the material seen); if panicoid type, nodular; not sharp-pointed.

Transverse section of leaf blade, physiology. C3; XyMS+. Leaf blade with distinct, prominent adaxial ribs, or ‘nodular’ in section; with the ribs more or less constant in size. Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups (in all the furrows); in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’ (in all the main bundles). Sclerenchyma all associated with vascular bundles.

Special diagnostic feature. Lemmas not as in Briza (q.v.). Female-fertile lemma not as in Lombardochloa (q.v.).

Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Poeae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Calothecinae. 2 species.

Distribution, phytogeography, ecology. South America.

Helophytic; glycophytic.

References, etc. Leaf anatomical: this project.

Illustrations. • M. poimorpha: Nicora & Rúgolo de Agrasar (1987)


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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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