The grass genera of the world
Habit, vegetative morphology. Perennial (?). Culms herbaceous. Leaves not basally aggregated; non-auriculate. Leaf blades linear to linear-lanceolate; narrow; about 4–6 mm wide; flat (pilose); not pseudopetiolate; without cross venation. Ligule an unfringed membrane (but abaxially hairy); not truncate (laciniate); about 5 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence few spikeleted; paniculate; open; espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets 10–13 mm long; compressed laterally; disarticulating above the glumes; not 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; shorter than the adjacent lemmas; hairless; pointed (acute); awnless; non-carinate; fairly similar (lanceolate, herbaceous). Lower glume 3 nerved. Upper glume 5 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets 1, or 2; merely underdeveloped; awned. Spikelets without proximal incomplete florets.
Female-fertile florets 1. Lemmas subcylindrical; decidedly firmer than the glumes (leathery); rigid; entire; awned. Awns 1; median; apical; non-geniculate, or geniculate (? - see illustration by Nicora and Rúgolo de Agrasar 1987); flexuous; hairless; much longer than the body of the lemma; persistent. Lemmas hairless; scabrous; non-carinate; without a germination flap; 5 nerved, or 7 nerved. Palea present; relatively long; tightly clasped by the lemma; apically notched; awnless, without apical setae; 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; glabrous; toothed; not or scarcely vascularized. Stamens 2. Ovary apically hairy (on the top); without a conspicuous apical appendage (not at all appendaged, just hairy). Styles free to their bases. Stigmas 2; white.
Fruit, embryo and seedling. Fruit medium sized (5 mm long); with hairs confined to a terminal tuft. Hilum long-linear. Embryo small.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells costal long-cells much smaller than intercostals. Mid-intercostal long-cells rectangular and fusiform; having markedly sinuous walls (and pitted, fairly thin-walled). Microhairs absent. Stomata absent or very rare. Intercostal short-cells common; in cork/silica-cell pairs (commonly); silicified. Numerous macrohairs present costally and intercostally. Costal short-cells predominantly paired. Costal silica bodies horizontally-elongated crenate/sinuous (a few), or rounded (numerous), or tall-and-narrow (a few); not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade. Leaf blade adaxially flat; with the ribs more or less constant in size. Midrib conspicuous (a larger bundle and an abaxially rounded keel); with one bundle only. Bulliforms present in discrete, regular adaxial groups; in simple fans (these large, mostly distorted by macrohairs). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming figures (all the bundles). Sclerenchyma all associated with vascular bundles.
Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Poeae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Loliinae. 1 species (P. bromoides).
Distribution, phytogeography, ecology. Juan Fernandez Is. (Chile).
References, etc. Morphological/taxonomic: Macfarlane and Watson 1980. Leaf anatomical: studied by us.
Illustrations. • P. bromoides: Nicora & Rúgolo de Agrasar (1987)
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’.