The grass genera of the world
Including Amblytes Dulac., Enodium Gaud., Moliniopsis Hayata
Habit, vegetative morphology. Perennial; caespitose. Culms 15–250 cm high; herbaceous; tuberous to not tuberous (the lowest internodes short, swollen, persisting for several years). Culm nodes glabrous. Culm internodes hollow. Leaves mostly basal (the intermediate internodes condensed, the uppermost constituting most of the elevated culm); non-auriculate. Leaf blades narrow; 3–10 mm wide; flat, or rolled; not pseudopetiolate; without cross venation; disarticulating from the sheaths; rolled in bud. Ligule a fringe of hairs.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets; outbreeding.
Inflorescence. Inflorescence paniculate; open, or contracted; with capillary branchlets; espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets 3.2–14 mm long; compressed laterally; disarticulating above the glumes; disarticulating between the florets; with distinctly elongated rachilla internodes between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; hairless (rough). Hairy callus present, or absent (M. coerulea). Callus short; blunt.
Glumes two; very unequal to more or less equal; shorter than the spikelets; shorter than the adjacent lemmas; pointed; awnless; carinate; similar (membranous). Lower glume 1–3 nerved. Upper glume 1–5 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–)2–5(–6). Lemmas decidedly firmer than the glumes (firmly membranous); not becoming indurated; entire; pointed (acute); awnless, or mucronate; hairless (somewhat scabrous above); non-carinate (rounded on the back); 3(–5) nerved. Palea present; relatively long; entire to apically notched (truncate to emarginate); awnless, without apical setae; 2-nerved. Lodicules present; 2; joined (at the base), or free; fleshy; glabrous. Stamens 3. Anthers 1.5–3 mm long; not penicillate. Ovary apically glabrous. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit free from both lemma and palea; small. Hilum long-linear. Pericarp loosely adherent (reluctantly separable). Embryo large; not waisted. Endosperm hard; without lipid; containing compound starch grains. Embryo without an epiblast; with a scutellar tail; with an elongated mesocotyl internode. Embryonic leaf margins meeting.
Seedling with a loose coleoptile. First seedling leaf with a well-developed lamina. The lamina narrow; 5 veined.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Mid-intercostal long-cells rectangular and fusiform; having markedly sinuous walls and having straight or only gently undulating walls. Microhairs present (in Moliniopsis), or absent (usually, in the rest); panicoid-type; in Moliniopsis (45–)48–54(–57) microns long; 6–8.4 microns wide at the septum. Microhair total length/width at septum 5.7–8.6. Microhair apical cells 24–27 microns long. Microhair apical cell/total length ratio 0.42–0.57. Stomata absent or very rare (Moliniopsis), or common; in Molinia sensu stricto (27–)30–34.5 microns long. Subsidiaries triangular (few), or dome-shaped (mostly, low). Intercostal short-cells common; in cork/silica-cell pairs; silicified. Intercostal silica bodies crescentic to tall-and-narrow, or vertically elongated-nodular. Costal short-cells conspicuously in long rows (but some of the short cells rather long). Costal silica bodies panicoid-type; cross shaped, or butterfly shaped, or dumb-bell shaped; not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma. Leaf blade with distinct, prominent adaxial ribs; with the ribs more or less constant in size. Midrib conspicuous; with one bundle only, or having a conventional arc of bundles. Bulliforms present in discrete, regular adaxial groups (at the bases of the shallow furrows); in simple fans. Combined sclerenchyma girders present; forming figures (at least in the mid-rib). Sclerenchyma all associated with vascular bundles.
Phytochemistry. Leaves without flavonoid sulphates (M. coerulea).
Cytology. Chromosome base number, x = 9. 2n = 18, 36, and 90. 2, 4, and 10 ploid. Chromosomes small.
Classification. Watson & Dallwitz (1994): Arundinoideae; Arundineae. Soreng et al. (2015): Arundinoideae; Molinieae. 2–5 species.
Distribution, phytogeography, ecology. Temperate Eurasia.
Helophytic (calcifuge); species of open habitats; glycophytic. Wet moorland, heaths.
Rusts and smuts. Rusts Puccinia. Taxonomically wide-ranging species: Puccinia graminis and Puccinia coronata. Smuts from Tilletiaceae. Tilletiaceae Neovossia.
References, etc. Morphological/taxonomic: Jir sek 1966. Leaf anatomical: Metcalfe 1960; this project.
Illustrations. • M. caerulea, general aspect: Eng. Bot. (1872). • General aspect (M. caerulea): John Curtis, 1824. • M. caerulea: Hitchcock (1920), Genera of U.S. Grasses
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’.