| # The grass genera of the world |

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

### Thamnocalamus Munro

Including Fargesia Franch., Himalayacalamus Keng f.

Habit, vegetative morphology. Perennial; caespitose. The flowering culms leafy. Culms 100–500 cm high; woody and persistent; to 2 cm in diameter; branched above. Buds from which the primary culm branches arise (where recorded) 1. Primary branches 3, or 4–10; horizontally aligned. The branching dendroid, or simple. Culm nodes without roots, glabrous. Culm leaf sheaths present; deciduous; not leaving a persistent girdle; where recorded, not conspicuously auriculate. Culm leaves with conspicuous blades. Culm leaf blades where recorded, triangular. Unicaespitose. Rhizomes pachymorph. Plants unarmed. Young shoots intravaginal. Leaves not basally aggregated; non-auriculate; without auricular setae. Leaf blades broad; pseudopetiolate; cross veined; disarticulating from the sheaths; rolled in bud. Ligule a fringed membrane; truncate; 1.5 mm long. Contra-ligule absent.

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

Inflorescence. Inflorescence determinate; without pseudospikelets; (synflorescences) a single raceme, or paniculate; contracted; spatheate; a complex of ‘partial inflorescences’ and intervening foliar organs. Spikelets solitary; not secund; pedicellate.

Female-fertile spikelets. Spikelets 15–18 mm long; oblong; not noticeably compressed. Rachilla prolonged beyond the uppermost female-fertile floret; hairless; the rachilla extension with incomplete florets. Hairy callus absent.

Glumes two; more or less equal; long relative to the adjacent lemmas; hairless; pointed; awnless (the upper pointed); non-carinate; similar. Lower glume 8–9 nerved. Upper glume 9–13 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 similar in texture to the glumes; smooth; not becoming indurated; entire; pointed; awnless, or mucronate (?); hairless; non-carinate; without a germination flap; 10–11 nerved. Palea present; relatively long; not convolute; apically notched; awnless, without apical setae; not indurated; several nerved; 2-keeled. Lodicules present; 3; free; 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 free to their bases. Stigmas 3.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present; costal and intercostal. Intercostal papillae over-arching the stomata (from the interstomatals); several per cell (small, thickened, one row per cell on the long-cells of astomatal zones, irregular on the interstomatals). Long-cells markedly different in shape costally and intercostally. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; panicoid-type. Stomata common. Subsidiaries parallel-sided, or dome-shaped, or parallel-sided and dome-shaped. Guard-cells overlapped by the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs and not paired (solitary and paired). Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies saddle shaped and ‘panicoid-type’; not sharp-pointed.

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; with adaxial palisade; with arm cells; with fusoids. The fusoids external to the PBS. Leaf blade adaxially flat (the ribbing at most slight). Midrib conspicuous; usually with one bundle only (complex in T. aristatus). The lamina symmetrical on either side of the midrib. Bulliforms present in discrete, regular adaxial groups; in simple fans, or 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.

Cytology. Chromosome base number, x = 12.

Classification. Watson & Dallwitz (1994): Bambusoideae; Bambusodae; Bambuseae. Soreng et al. (2015): Bambusoideae; Arundinarodae; Arundinarieae; Arundinariinae. 6 species.

Distribution, phytogeography, ecology. Eastern Asia.

Helophytic, or mesophytic; glycophytic.

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: Soderstrom and Ellis 1982.

Special comments. See Clayton and Renvoize (1986) and Soderstrom and Ellis (1987) for the former, completely different generic interpretations of the species in this circle of affinity. Fruit data wanting.

Illustrations. • Thamnocalamus tessellatus, as Arundinaria: Hook. Ic. Pl. 30 (1913). • General morphology (T. tessellatus): Gibbs Russell et al., 1990. • Thamnocalamus spathiflorus (with Phyllostachys spp.): 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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