| # The grass genera of the world |

L. Watson, T.D. Macfarlane, and M.J. Dallwitz

### Chimonobambusa Makino

Including Menstruocalamus, Oreocalamus Keng, Qiongzhuea Hsueh & Yi

Habit, vegetative morphology. Perennial; rhizomatous, or stoloniferous. The flowering culms leafy. Culms 50–600 cm high; woody and persistent (monopodial); to 0.8–3 cm in diameter; branched above. Buds from which the primary culm branches arise (where recorded) 3. Primary branches 3 (usually), or 4–10; horizontally aligned. The branching dendroid (nearly always), or suffrutescent. Culm leaf sheaths present; deciduous, or persistent; conspicuously auriculate (rarely), or not conspicuously auriculate. Culm leaves with conspicuous blades, or without conspicuous blades. Culm leaf blades when present, linear (often), or lanceolate, or ovate, or triangular. Culm internodes hollow. Rhizomes leptomorph. Plants conspicuously armed (the two-ridged culm nodes usually thorny). Leaves not basally aggregated; with auricular setae. Leaf blades broad, or narrow; pseudopetiolate; cross veined, or without cross venation; disarticulating from the sheaths (or at least demarcated); rolled in bud. Contra-ligule present (nearly always), or absent (C. gracilis only).

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.

Inflorescence. Inflorescence determinate, or indeterminate; seemingly without pseudospikelets; exhibiting 1–12 spikelets at each node of leafy or leafless branches; non-digitate; spatheate; a complex of ‘partial inflorescences’ and intervening foliar organs (inflorescence branches with or without foliage leaves). Spikelet-bearing axes ‘racemes’, or paniculate; persistent. Spikelets not secund; sessile.

Female-fertile spikelets. Spikelets linear (nearly always), or elliptic (e.g., C. damingshamensis); disarticulating above the glumes; disarticulating between the florets (?); with distinctly elongated rachilla internodes between the florets (‘the florets distant’). Rachilla prolonged beyond the uppermost female-fertile floret (?); the rachilla extension with incomplete florets. Hairy callus absent.

Glumes two to several; very unequal; shorter than the adjacent lemmas; awnless. Lower glume 3 nerved. Upper glume 7 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped.

Female-fertile florets 2–8 (?). Lemmas ovate, membranous; entire; pointed; awnless; 8 nerved. Palea present; relatively long; not convolute; entire; several nerved (7 observed); 2-keeled. Lodicules present; 3; free; membranous; ciliate; not toothed; heavily vascularized. Stamens 3. Anthers without an apically prolonged connective. Ovary apically glabrous; without a conspicuous apical appendage. Styles free to their bases (apparently). Stigmas 2 (feathery).

Fruit, embryo and seedling. Fruit not grooved; not noticeably compressed. Hilum short. Pericarp fleshy (at least, in Subg. Oreocalamus and Quiongzhuea); free. Seed ‘non-endospermic’.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present; costal and intercostal. Intercostal papillae conspicuously over-arching the stomata; several per cell (mostly one row per cell, of the coronate-pit type, cf. Poa helmsii). Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; panicoid-type (but large and fat); (54–)63–69 microns long (in C. densifolia); 6–9 microns wide at the septum. Microhair total length/width at septum 6–11.5 (i.e. very variable in C. densifolia). Microhair apical cells (21–)24–27 microns long. Microhair apical cell/total length ratio 0.35–0.43. Stomata common; about 27 microns long (in C. densifolia). Subsidiaries non-papillate; parallel-sided to dome-shaped. Intercostal short-cells common; not paired (mostly solitary); not silicified (mostly). Costal short-cells neither distinctly grouped into long rows nor predominantly paired (ones and twos). Costal silica bodies saddle shaped and oryzoid.

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade; with arm cells; with fusoids. The fusoids external to the PBS. Leaf blade with the ribs more or less constant in size. Midrib conspicuous (a larger bundle, with massive I-configuration of girders); 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 all the bundles); forming ‘figures’ (all narrow I’s, except midrib). Sclerenchyma all associated with vascular bundles.

Cytology. Chromosome base number, x = 12. 2n = 48. 4 ploid. Chromosomes ‘small’.

Classification. Watson & Dallwitz (1994): Bambusoideae; Bambusodae; Bambuseae. Soreng et al. (2015): Bambusoideae; Arundinarodae; Arundinarieae; Arundinariinae. 10 species.

Distribution, phytogeography, ecology. Eastern Asia and Himalaya.

Rusts and smuts. Rusts — Stereostratum. Taxonomically wide-ranging species: Stereostratum corticoides.

References, etc. Morphological/taxonomic: Chao and Renvoize 1989. Leaf anatomical: studied by us - C. densifolia Nakai.

Special comments. Fruit data wanting.

Illustrations. • Chimonobambusa callosa (as Arundinaria: Camus, 1913). • Abbreviations for Camus (1913) figures.

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: 15th June 2025. delta-intkey.com’.

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