The grass genera of the world
Habit, vegetative morphology. Slender perennial (with dimorphic culms); caespitose. The flowering culms leafless (with 1–3 bladeless sheaths). Culms 10–25 cm high (the vegetative culms 3–12 cm tall, the flowering culms longer); herbaceous; unbranched above; tuberous. Rhizomes pachymorph. Plants unarmed. Young shoots intravaginal. Leaves not basally aggregated; without auricular setae. Leaf blades elliptic; narrow (but relatively broad); 3–5 mm wide (and 8–18 mm long); not cordate, not sagittate (base cuneate, no more than slightly asymmetric); flat; shortly pseudopetiolate; persistent; rolled in bud. Ligule an unfringed membrane, or a fringed membrane (?- a hyaline, lacerate, ciliate membrane); truncate; about 0.1 mm long.
Reproductive organization. Plants monoecious with all the fertile spikelets unisexual; without hermaphrodite florets. The spikelets of sexually distinct forms on the same plant; male-only and sterile. The male and female-fertile spikelets on different branches of the same inflorescence. The spikelets overtly heteromorphic.
Inflorescence. Inflorescence of spicate main branches (of two spike-like racemes, the one male, the somewhat longer one female); digitate. Primary inflorescence branches 2. Inflorescence espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes racemes; persistent. Spikelets solitary; secund (on one side of the slender, triquetrous rachis); pedicellate (with very short, clavate pedicels); not in distinct long-and-short combinations.
Female-sterile spikelets. The male racemes slightly shorter; male spikelets 1.3--1.7 mm long, much shorter than females, ellipsoid, acute; lemma 1-nerved, palea 2-nerved, lemma and palea membranous; 3 free, non-penicillate stamens. Rachilla of male spikelets terminated by a male floret. The male spikelets without glumes; without proximal incomplete florets; 1 floreted. The lemmas awnless. Male florets 1; 3 staminate. The staminal filaments free.
Female-fertile spikelets. Spikelets 2–4.5 mm long; narrowly elliptic; compressed dorsiventrally; with conventional internode spacings (i.e. no stipe above the glumes). Rachilla terminated by a female-fertile floret. Hairy callus absent.
Glumes two; relatively large; very unequal to more or less equal (the lower somewhat shorter); shorter than the spikelets; shorter than the adjacent lemmas; hairless; pointed to not pointed; awnless; non-carinate; similar (delicately membranous, ovate-elliptical). Spikelets with female-fertile florets only.
Female-fertile florets 1. Lemmas similar in texture to the glumes, or decidedly firmer than the glumes (membranous); becoming indurated (white-cartilaginous); entire; pointed, or blunt; awnless (and not apiculate); hairless; glabrous; non-carinate; having the margins inrolled against the palea. Palea present; relatively long; entire; awnless, without apical setae (glabrous); textured like the lemma (which enfolds it); indurated. Lodicules present; 3. Stamens 0 (and no vestiges).
Fruit, embryo and seedling. Disseminule a free caryopsis. Fruit free from both lemma and palea; small (1.5–2 mm long); fusiform; longitudinally grooved; compressed dorsiventrally. Hilum long-linear. Embryo small.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present; costal and intercostal. Intercostal papillae over-arching the stomata, or not over-arching the stomata; several per cell (small, numerous, and often forming rings around the stomata). Long-cells markedly different in shape costally and intercostally (the costals much narrower); of similar wall thickness costally and intercostally (thin walled). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; elongated; clearly two-celled; panicoid-type; 36–46 microns long; 6.3–7.5 microns wide at the septum. Microhair total length/width at septum 9–10.2. Microhair apical cells 8–15 microns long. Microhair apical cell/total length ratio 0.2–0.4. Stomata common; 13–17 microns long. Subsidiaries non-papillate; parallel-sided. Guard-cells overlapped by the interstomatals (slightly). Intercostal short-cells absent or very rare. No macrohairs, but hooks and prickles common. Costal short-cells conspicuously in long rows. Costal silica bodies panicoid-type; predominantly short dumb-bell shaped.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with adaxial palisade; with arm cells; without fusoids. Leaf blade adaxially flat. Midrib conspicuous (by virtue of its large bundle and relatively massive anchor of sclerenchyma); with one bundle only. The lamina symmetrical on either side of the midrib. Bulliforms present in discrete, regular adaxial groups; in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming figures (most bundles with an anchor). Sclerenchyma all associated with vascular bundles.
Classification. Watson & Dallwitz (1994): Bambusoideae; Oryzodae; Olyreae. Soreng et al. (2015): Bambusoideae; Bambusodae; Olyreae; Olyrinae. 1 species (M. pulchella).
Distribution, phytogeography, ecology. Cuba.
Mesophytic; shade species. On lowland limestone cliffs.
References, etc. Morphological/taxonomic: Chase 1908; Zuloaga et al. 1993. Leaf anatomical: Zuloaga et al. 1993.
Special comments. Fruit data wanting. Illustrations. • M. pulchella: Hitchcock (1936)
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: 11th December 2017. delta-intkey.com/grass’.