The grass genera of the world
Type species: Type: M. minutiflora P.Beauv.
Including Suaria Schrank, Tristegis Nees
Habit, vegetative morphology. Annual, or perennial; decumbent. Culms 30–120 cm high; herbaceous. Culm nodes hairy. Culm leaf sheaths rounded. Culm internodes solid to hollow. The shoots aromatic. Leaves not basally aggregated; non-auriculate. Leaf blades narrow; without cross venation; persistent. Ligule a fringed membrane (very narrow), or a fringe of hairs.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate; open; with capillary branchlets (flexuose). Primary inflorescence branches inserted all around the main axis. Inflorescence espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate; not in distinct long-and-short combinations.
Female-fertile spikelets. Spikelets 1–4 mm long; oblong; not noticeably compressed to compressed dorsiventrally; falling with the glumes; with conventional internode spacings. Rachilla terminated by a female-fertile floret. Hairy callus absent.
Glumes one per spikelet, or two; very unequal; (the upper) long relative to the adjacent lemmas; awned, or awnless; very dissimilar (the lower tiny, membranous or reduced to a rim, the upper equalling spikelet, truncate, emarginate or bifid at summit, often awned from the sinus, straight on the back). Lower glume 0 nerved. Upper glume 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, or epaleate. Palea of the proximal incomplete florets when present, fully developed. The proximal incomplete florets male, or sterile. The proximal lemmas awned (usually, with a subulate awn from the bifid apex), or awnless (rarely); 3–5 nerved; similar in texture to the female-fertile lemmas, or decidedly firmer than the female-fertile lemmas; not becoming indurated.
Female-fertile florets 1. Lemmas less firm than the glumes (hyaline or thinly membranous); smooth; not becoming indurated; white in fruit; entire, or incised; awnless; hairless; carinate; having the margins lying flat on the palea; without a germination flap; 1–3 nerved. Palea present; relatively long; textured like the lemma; not indurated; 2-nerved; keel-less (or flattened). Lodicules present; 2; fleshy, or membranous. Stamens 3. Anthers not penicillate. Ovary apically glabrous. Styles basally fused to free to their bases. Stigmas 2; white, or brown.
Fruit, embryo and seedling. Hilum short. Embryo large. Endosperm containing only simple starch grains. Embryo without an epiblast; with a scutellar tail; with an elongated mesocotyl internode. Embryonic leaf margins overlapping.
Seedling with a long mesocotyl. First seedling leaf with a well-developed lamina. The lamina broad; curved; 13–20 veined.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; panicoid-type; 63–70.5 microns long; 5.4–6 microns wide at the septum. Microhair total length/width at septum 11–13. Microhair apical cells 30–34.5 microns long. Microhair apical cell/total length ratio 0.47–0.5. Stomata common; 30–33 microns long. Subsidiaries low dome-shaped and triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells absent or very rare. Prickle bases abundant. Costal short-cells conspicuously in long rows. Costal silica bodies panicoid-type; cross shaped, or butterfly shaped, or butterfly shaped, or dumb-bell shaped; not sharp-pointed.
Transverse section of leaf blade, physiology. C4; biochemical type PCK (M. minutiflora); XyMS+. PCR sheath outlines uneven. PCR cell chloroplasts ovoid; centrifugal/peripheral. Mesophyll with radiate chlorenchyma. Leaf blade adaxially flat. Midrib conspicuous; having a conventional arc of bundles. Bulliforms present in discrete, regular adaxial groups; associated with colourless mesophyll cells to form deeply-penetrating fans. Many of the smallest vascular bundles unaccompanied by sclerenchyma. Combined sclerenchyma girders present. Sclerenchyma all associated with vascular bundles.
Culm anatomy. Culm internode bundles in three or more rings.
Phytochemistry. Leaves without flavonoid sulphates (2 species). Leaf blade chlorophyll a:b ratio 3.31–3.46.
Cytology. Chromosome base number, x = 9. 2n = 36.
Classification. Watson & Dallwitz (1994): Panicoideae; Panicodae; Paniceae (Melinideae). Soreng et al. (2015): Panicoideae; Panicodae; Paniceae; Melidininae. About 12 species.
Distribution, phytogeography, ecology. 1 in tropical South America, West Indies; 11 in tropical and South Africa, Madagascar.
Commonly adventive. Helophytic, or mesophytic; shade species and species of open habitats; glycophytic. Savanna woodland, open grassland and disturbed ground.
Economic aspects. Cultivated fodder: M. minutiflora. Important native pasture species: M. minutiflora.
Rusts and smuts. Rusts Physopella and Puccinia. Taxonomically wide-ranging species: Uromyces setariae-italicae.
References, etc. Leaf anatomical: Metcalfe 1960 and this project.
Illustrations. • M. minutiflora: P. Beauv. (1812). • M. minutiflora: Fl. W. Trop. Afr. (1936). • M. minutiflora: Gardner, 1952. • M. tenuissima: Hook. Ic. Pl. 27 (1900). • General aspect (M. macrochaeta): Gibbs Russell et al., 1990
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: 13th November 2017. delta-intkey.com/grass’.