The grass genera of the world
Rats tail fescue.
Type species: Type: V. myurus (L.) C.C.Gmel.
Including Chloammia Rafin., Distomomischus Dulac, Festucaria Link, Loretia Duval-Jouve, Mygalurus Link, Narduretia Villar, Nardurus (Bluff, Nees & Schauer) Reichenb., Prosphysis Dulac, Zerna Panzer
Habit, vegetative morphology. Annual, or perennial (rarely); caespitose. Culms 5–90 cm high; herbaceous; unbranched above. Culm nodes glabrous. Culm internodes solid, or hollow. Young shoots intravaginal. Leaves not basally aggregated; non-auriculate. Sheath margins free. Leaf blades linear; apically cucullate; narrow; 0.5–3 mm wide; setaceous to not setaceous; flat, or rolled (convolute when dry); without cross venation; persistent; rolled in bud. Ligule an unfringed membrane; truncate, or not truncate; 0.2–6 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets; inbreeding; exposed-cleistogamous, or chasmogamous.
Inflorescence. Inflorescence a single raceme (rarely), or paniculate; open, or contracted; when contracted spicate, or more or less irregular. Primary inflorescence branches borne biseriately on one side of the main axis. Inflorescence espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets usually more or less secund; pedicellate.
Female-fertile spikelets. Spikelets 5–16 mm long; compressed laterally; disarticulating above the glumes (also, sometimes, at the base of the pedicel); disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; hairy, or hairless; the rachilla extension with incomplete florets. Hairy callus absent. Callus short.
Glumes two; very unequal; shorter than the spikelets; shorter than the adjacent lemmas, or long relative to the adjacent lemmas; free; dorsiventral to the rachis; pointed; awned (G2, sometimes), or awnless; non-carinate; very dissimilar (usually, the G1 often minute, the G2 acute to acuminate). Lower glume 0 nerved, or 1 nerved. Upper glume 1 nerved, or 3 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. Spikelets without proximal incomplete florets.
Female-fertile florets 2–15 (rarely only 1). Lemmas tapered; similar in texture to the glumes to decidedly firmer than the glumes (chartaceous, with thin margins); not becoming indurated; entire; pointed; awned. Awns 1; median; apical; non-geniculate; much shorter than the body of the lemma to much longer than the body of the lemma; entered by one vein. Lemmas hairy, or hairless; carinate to non-carinate; 3–5 nerved. Palea present; relatively long; apically notched; awnless, without apical setae; not indurated; 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; glabrous; toothed, or not toothed. Stamens 1–2 (rarely 3). Anthers 0.3–5 mm long; not penicillate. Ovary apically glabrous, or apically hairy. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit adhering to lemma and/or palea; small, or medium sized, or large; longitudinally grooved; compressed dorsiventrally; with hairs confined to a terminal tuft. Hilum long-linear. Embryo small; not waisted. Endosperm hard; with lipid; containing compound starch grains. Embryo with an epiblast; without a scutellar tail; with a negligible mesocotyl internode.
Seedling with a tight coleoptile. First seedling leaf with a well-developed lamina. The lamina narrow; erect; 1–3 veined.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally. Mid-intercostal long-cells rectangular, or fusiform; having markedly sinuous walls. Microhairs absent. Stomata absent or very rare, or common; when present, (36–)39–51(–54) microns long. Subsidiaries parallel-sided. Guard-cells overlapped by the interstomatals, or overlapping to flush with the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs (mainly), or not paired (solitary); silicified (when paired). Costal zones with short-cells. Costal short-cells predominantly paired. Costal silica bodies horizontally-elongated crenate/sinuous, or horizontally-elongated smooth (a few), or rounded, or crescentic; not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade. Leaf blade with distinct, prominent adaxial ribs; with the ribs more or less constant in size. Midrib conspicuous; with one bundle only. Bulliforms present in discrete, regular adaxial groups (at the bases of the furrows); in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders absent. Sclerenchyma all associated with vascular bundles.
Phytochemistry. Tissues of the culm bases with little or no starch.
Cytology. Chromosome base number, x = 7. 2n = 14, 28, and 42. 2, 4, and 6 ploid. Chromosomes large.
Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Poeae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Loliinae. 23 species.
Distribution, phytogeography, ecology. Temperate.
Commonly adventive. Mesophytic, or xerophytic; species of open habitats; halophytic (sometimes), or glycophytic. Dry places, including coastal sand.
Economic aspects. Significant weed species: V. bromoides, V. myuros.
Hybrids. Intergeneric hybrids with Festuca - ×Festulpia Melderis ex Stace & R. Cotton (several species involved).
Rusts and smuts. Rusts Puccinia. Taxonomically wide-ranging species: Puccinia graminis, Puccinia coronata, Puccinia brachypodii, Puccinia hordei, Puccinia recondita, Uromyces fragilipes, and Uromyces dactylidis. Smuts from Tilletiaceae and from Ustilaginaceae. Tilletiaceae Entyloma and Tilletia. Ustilaginaceae Ustilago.
References, etc. Morphological/taxonomic: Cotton and Stace 1977, Stace 1981. Leaf anatomical: this project.
Illustrations. • V. ciliata var. ambigua (as Festuca ambigua), general aspect: Eng. Bot. (1872). • V. myuros: Gardner, 1952. • V. myuros (as Festuca pseudo-myuros, general aspect: Eng. Bot. (1872). • V. membranacea (as Festuca uniglumis), general aspect: Eng. Bot. (1872). • Spikelet of V. bromoides. • V. bromoides (as Festuca sciuroides), general aspect: Eng. Bot. (1872). • V. bromoides, abaxial epidermis of leaf blade: this project
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’.