The grass genera of the world
Type species: Y. alpina (K. Schum.) W.C. Lin.
Habit, vegetative morphology. Perennial; rhizomatous and caespitose. The flowering culms leafy. Culms 100–400 cm high; woody and persistent; to 2 cm in diameter; branched above. Buds from which the primary culm branches arise consistently 1. Primary branches (1–)3–20. The branching dendroid (mostly), or suffrutescent. Culm leaf sheaths present; deciduous, or persistent; conspicuously auriculate, or not conspicuously auriculate. Culm leaves with conspicuous blades. Culm leaf blades linear, or lanceolate, or triangular. Culm internodes hollow. Pluricaespitose. Rhizomes metamorph type II. Plants unarmed. Leaves not basally aggregated; auricles inconspicuous; with auricular setae (short brown bristles). Leaf blades lanceolate; broad, or narrow; 5–13 mm wide (4–18 cm long); pseudopetiolate; cross veined; demarcated, disarticulating from the sheaths, or disarticulating from the sheaths to persistent; rolled in bud. Ligule present. Contra-ligule present (very rarely - e.g., Y. glandulosa), or absent.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. Not viviparous.
Inflorescence. Inflorescence with pseudospikelets, or without pseudospikelets; paniculate (with few spikelets per synflorescence cluster); spatheate; a complex of partial inflorescences and intervening foliar organs. Spikelet-bearing axes spikelike, or paniculate; persistent. Spikelets not secund; distichous; pedicellate.
Female-fertile spikelets. Spikelets morphologically conventional, or unconventional; where recorded, lanceolate, or obovate; compressed laterally; disarticulating above the glumes; disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; hairy (at the swollen tips of the joints); the rachilla extension with incomplete florets. Hairy callus absent.
Glumes two; shorter than the adjacent lemmas; pointed; awnless (acute to acuminate-tipped); carinate; similar. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped. Spikelets without proximal incomplete florets.
Female-fertile florets 2–7. Lemmas similar in texture to the glumes; not becoming indurated; entire; pointed; mucronate to awned. Awns 1; median; apical; non-geniculate; much shorter than the body of the lemma. Lemmas carinate; 7 nerved, or 9 nerved. Palea present; relatively long; convolute around the flower, or not convolute; apically notched (acutely bifid); not indurated; several nerved (2 between the keels, 2 between each keel and the margin); 2-keeled. Lodicules present; 3; joined; membranous; ciliate; not toothed; heavily vascularized. Stamens 3. Anthers not penicillate; without an apically prolonged connective. Ovary apically glabrous; without a conspicuous apical appendage. Styles fused. Stigmas 2.
Fruit, embryo and seedling. Fruit longitudinally grooved; compressed dorsiventrally. Hilum long-linear. Embryo small.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present. Mid-intercostal long-cells having markedly sinuous walls (these thin). Microhairs present; panicoid-type. Stomata common. Costal short-cells predominantly paired, or neither distinctly grouped into long rows nor predominantly paired, or conspicuously in long rows (sometimes, over main veins). Costal silica bodies saddle shaped (commonly), or oryzoid to panicoid-type (sometimes tending to cross-shaped, then sometimes tending to be vertically elongated).
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll without adaxial palisade; with arm cells; with fusoids. The fusoids external to the PBS. Leaf blade with distinct, prominent adaxial ribs. Midrib conspicuous; having complex vascularization. The lamina distinctly asymmetrical on either side of the midrib. Bulliforms present in discrete, regular adaxial groups; in simple fans (mostly), or in simple fans and associated with colourless mesophyll cells to form deeply-penetrating fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming figures. Sclerenchyma all associated with vascular bundles.
Classification. Watson & Dallwitz (1994): Bambusoideae; Bambusodae; Bambuseae. Soreng et al. (2015): Bambusoideae; Arundinarodae; Arundinarieae; Arundinariinae. 1 species (Y. alpina).
Distribution, phytogeography, ecology. China including Taiwan.
References, etc. Morphological/taxonomic: See Stapleton, C.M.A. (1013). Bergbambos and Oldeania, new genera of African bamboos (Poaceae, Bambusoideae). PhytoKeys 25: 87–103. Leaf anatomical: this project.
Special comments. Clayton and Renvoize (1986) and Soderstrom and Ellis (1987) proposed different generic interpretations of species in this circle of affinity. Anatomical data more or less satisfactory (but slides to be re-examined). Illustrations. • Y. walkeriana, as Arundinaria: Gamble (1896), Ann. R. Bot. Gard. Calcutta 7. • Y. floribunda, as Arundinaria: Gamble (1896), Ann. R. Bot. Gard. Calcutta 7
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’.