The grass genera of the world
~ Festuca (F. albida)
Habit, vegetative morphology. Perennial; densely caespitose. Culms 25–100 cm high; herbaceous; unbranched above. Young shoots intravaginal. Leaves non-auriculate. Sheath margins free. The sheaths splitting longitudinally into fibres. Leaf blades linear; broad to narrow; 3–10 mm wide (-12); flat, or rolled (convolute); not pseudopetiolate; without cross venation; persistent. Ligule an unfringed membrane; truncate; 0.8–2 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate; open to contracted; espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets 6–8(–10) mm long; compressed laterally; disarticulating above the glumes; disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets. Hairy callus present. Callus short.
Glumes two; very unequal; shorter than the spikelets; long relative to the adjacent lemmas; hairless; scabrous (marginally and below); pointed; awnless; carinate; similar (lanceolate). Lower glume 1 nerved. Upper glume 3 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped.
Female-fertile florets 2–3(–4). Lemmas similar in texture to the glumes; not becoming indurated; entire; pointed; awnless; hairless; scabrous (on the keel); carinate; 3 nerved. Palea present; relatively long to conspicuous but relatively short; apically notched; awnless, without apical setae; not indurated; 2-nerved; 2-keeled. Palea keels wingless; scabrous to hairy (below). Lodicules present; 2; free; membranous; glabrous; toothed (the teeth equal); not or scarcely vascularized. Stamens 3. Anthers 2.5–3 mm long. Ovary apically glabrous. Stigmas 2.
Fruit, embryo and seedling. Fruit small to medium sized (3.5 – 4 mm long); fusiform; somewhat compressed dorsiventrally (ventrally). Hilum short. Embryo small.
Transverse section of leaf blade, physiology. C3. Leaf blade with distinct, prominent adaxial ribs; with the ribs very irregular in sizes. Midrib conspicuous; with one bundle only. Bulliforms present in discrete, regular adaxial groups; in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with the main bundles only); forming figures (in the main bundles).
Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Poeae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Aveninae. 1 species (P. albida).
Distribution, phytogeography, ecology. Madeira.
References, etc. Morphological/taxonomic: Alekseev 1985. Leaf anatomical: Alekseev 1985, and studied by us.
Special comments. Anatomical data for ts only.
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’.