The grass genera of the world
Habit, vegetative morphology. Rather rigid annual. Culms 10–30 cm high; herbaceous. Leaves non-auriculate. Leaf blades linear; narrow; not setaceous; rolled (convolute); without cross venation. Ligule an unfringed membrane; not truncate; 1.5–2.5 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality.
Inflorescence. Inflorescence a single raceme (spike-like, the pedicels short); espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; secund; subsessile to pedicellate (the pedicels 0.2 to 0.6 mm long); imbricate.
Female-fertile spikelets. Spikelets 3.5–8 mm long; compressed laterally; disarticulating above the glumes; tardily disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets. Hairy callus absent.
Glumes two (leathery, the midrib thickened); more or less equal; long relative to the adjacent lemmas; displaced (the G1 orientated parallel to the rachilla on the flattened side of the spikelet); pointed (acute); awnless; carinate; very dissimilar (the lower linear, subulate, the upper lanceolate). Lower glume 1 nerved. Upper glume 2 nerved, or 3 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped.
Female-fertile florets 3–11. Lemmas similar in texture to the glumes (leathery, the margins membranous); not becoming indurated; entire; pointed, or blunt (acuminate to obtuse-apiculate); awnless; hairy; more or less carinate; without a germination flap; 5 nerved. Palea present; relatively long; apically notched (shortly bifid); awnless, without apical setae; 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; glabrous; toothed; not or scarcely vascularized. Stamens 3. Anthers 2–2.5 mm long. Ovary apically glabrous. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit free from both lemma and palea; small (1.8–2.4 mm long); compressed dorsiventrally. Hilum short. Embryo small; with an epiblast; without a scutellar tail; with a negligible mesocotyl internode. Embryonic leaf margins meeting.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous (costal silica-bodies larger). Papillae absent. Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular; having markedly sinuous walls (coarsely). Microhairs absent. Stomata absent or very rare. Intercostal short-cells common; nearly all in cork/silica-cell pairs; silicified. Crown cells present (over the veins). Costal zones with short-cells. Costal short-cells predominantly paired. Costal silica bodies horizontally-elongated crenate/sinuous (a few, short), or rounded (mostly, more or less irregular); 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 not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups; in simple fans. All the vascular bundles accompanied by sclerenchyma (but scanty sclerenchyma). Combined sclerenchyma girders absent (strands only). Sclerenchyma all associated with vascular bundles (save at the blade margins).
Cytology. Chromosome base number, x = 7. 2n = 14. 2 ploid.
Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Poeae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Loliinae. 2 species.
Distribution, phytogeography, ecology. Spain, North Africa.
Species of open habitats.
References, etc. Leaf anatomical: studied by us - W. lima (L.) Trin.
Illustrations. • W. lima, as Cynosurus: Cavanilles (1771), Ic. et Desc. Plantarum, vol. 1. • W. lima, as Cynosuus: Desfontaines (1798), Flora Atlantica vol. 1. • W. lima, 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: 11th December 2017. delta-intkey.com/grass’.