The grass genera of the world
Type species: P. somae Hayata.
Habit, vegetative morphology. Decumbent (culm bases creeping, with rooting nodes). Culms 30–40 cm high; herbaceous. Leaf blades lanceolate; narrow; to 5 mm wide; without cross venation. Ligule truncate.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality; homomorphic.
Inflorescence. Inflorescence of spicate main branches, or paniculate (?- of paired racemes); non-digitate; espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes racemes; paired (slender, recurved, about 8 cm long); persistent (?-rachis tough). Articles linear. Spikelets paired; pedicellate; consistently in long-and-short combinations; unequally pedicellate in each combination. Pedicels of the pedicellate spikelets free of the rachis. The shorter spikelets hermaphrodite. The longer spikelets hermaphrodite.
Female-fertile spikelets. Spikelets 5 mm long; compressed dorsiventrally; falling with the glumes. Rachilla terminated by a female-fertile floret. Hairy callus present.
Glumes two; long relative to the adjacent lemmas; awned; very dissimilar (the G1 2-aristate with 1 mm aristules, the G2 acuminate into an 8 mm awn). Lower glume flattened on the back; not pitted; relatively smooth. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. The proximal incomplete florets 1; epaleate; sterile. The proximal lemmas hyaline, linear, 2-toothed; awned (the awn long, geniculate, from the sinus); more or less equalling the female-fertile lemmas; similar in texture to the female-fertile lemmas.
Female-fertile florets 1. Lemmas linear, similar to the L1 in texture and form; less firm than the glumes (hyaline); incised; 2 lobed; not deeply cleft (bidentate); awned. Awns 1; median; from a sinus; geniculate; hairy; much longer than the body of the lemma (about 10 mm long). Lemmas hairless; non-carinate; without a germination flap. Palea present, or absent (?); if present, very reduced. Lodicules present; 2; free; fleshy; glabrous. Ovary apically glabrous (?). Stigmas 2.
Fruit, embryo and seedling. Hilum short.
Classification. Watson & Dallwitz (1994): Panicoideae; Andropogonodae; Andropogoneae; Andropogoninae. Soreng et al. (2015): Panicoideae; Andropogonodae; Andropogoneae; Saccharinae. 1 species (P. somae).
Distribution, phytogeography, ecology. Formosa.
References, etc. Morphological/taxonomic: Hayata 1918.
Special comments. Fruit data wanting. Anatomical data wanting. Illustrations. • P. somai, spikelet details: B. Hayata, Ic. Pl. formosanarum (1918)
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’.