| # The grass genera of the world |

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

### Indocalamus Nakai

Excluding (supposedly) Gelidocalamus Wen, Ferrocalamus Hsueh & Keng f., Monocladus

Habit, vegetative morphology. Perennial (shrubs). The flowering culms leafy. Culms slender, 60–300 cm high; woody and persistent; branched above. Buds from which the primary culm branches arise (where recorded) 1. Primary branches 1–3 (commonly), or 4–20. The branching simple (commonly), or suffrutescent (?), or dendroid. Culm leaf sheaths present; persistent; conspicuously auriculate, or not conspicuously auriculate. Culm leaves with conspicuous blades. Culm leaf blades linear, or lanceolate, or ovate, or triangular. Rhizomes leptomorph. Plants unarmed. Leaves not basally aggregated; with auricular setae. Leaf blades broad, or narrow; 5–25 mm wide; cordate, or not cordate, not sagittate; pseudopetiolate; cross veined, or without cross venation; where recorded, disarticulating from the sheaths; rolled in bud. Ligule present; a fringed membrane; short. Contra-ligule consistently absent.

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

Inflorescence. Inflorescence paniculate; spatheate, or espatheate (the panicles spatheate or not, terminating leafy or leafless shoots); a complex of ‘partial inflorescences’ and intervening foliar organs, or not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes paniculate; persistent. Spikelets not secund.

Female-fertile spikelets. Spikelets 8–18 mm long; oblong, or lanceolate, or linear (commonly); with distinctly elongated rachilla internodes between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets.

Glumes two; very unequal; shorter than the adjacent lemmas; awnless; similar (membranous). Lower glume 9 nerved (in material seen). Upper glume 9 nerved (in material seen). Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. Spikelets without proximal incomplete florets.

Female-fertile florets 3–8. Lemmas sometimes tessellate; 7 nerved, or 9 nerved (in material seen). Palea present; relatively long; not convolute; several nerved (3–5 nerved in material seen); 2-keeled. Stamens 3. Ovary where recorded, without a conspicuous apical appendage. Stigmas 2.

Fruit, embryo and seedling. Fruit longitudinally grooved, or not grooved. Pericarp fleshy (at least, in Ferrocalamus, Wen and He 1989), or thin (?); fused. Seed endospermic. Endosperm containing compound starch grains.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present (large, thick-walled); costal and intercostal. Intercostal papillae over-arching the stomata; several per cell (one row per cell). Mid-intercostal long-cells rectangular; having markedly sinuous walls (these thin). Microhairs present; panicoid-type; 45–52.5 microns long (in I. debilis); 5.1–6 microns wide at the septum. Microhair total length/width at septum 7.5–10.2. Microhair apical cells 21–25.5 microns long. Microhair apical cell/total length ratio 0.47–0.5. Stomata common (alongside the veins); 24–28.5 microns long (in I. debilis). Subsidiaries parallel-sided and dome-shaped. Guard-cells overlapped by the interstomatals. Intercostal short-cells common; not paired; silicified. Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies ‘panicoid-type’.

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. Midrib conspicuous (larger bundle); 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; forming ‘figures’ (with most bundles). Sclerenchyma all associated with vascular bundles.

Cytology. Chromosome base number, x = 12. 2n = 48. 4 ploid.

Classification. Watson & Dallwitz (1994): Bambusoideae; Bambusodae; Bambuseae. Soreng et al. (2015): Bambusoideae; Arundinarodae; Arundinarieae (including synonyms Ferrocalamus, Gelidocalamus, etc.); Arundinariinae. 6 species.

Distribution, phytogeography, ecology. Tropical Asia.

Paleotropical.

Woodland, and forming thickets in open country.

Economic aspects. Leaves of I. longiauritus and I. sinicus used for wrapping Chinese tamales, for lining baskets, for roofing boats etc.

References, etc. Leaf anatomical: studied by us - I. debilis (Thwait.) Alston.

Special comments. Fruit data wanting.

Illustrations. • Indocalamus tessellatus (as Sasa, Camus 1913). • Abbreviations for Camus (1913) figures. • Indocalamus latifolius, with Bonia (= Monocladus) saxatilis: Wu Zhengyi, Flora Yunnanica 9 (2003). • Indocalamus debilis, abaxial epidermis of leaf blade: this project. • Indocalamus debilis, abaxial epidermis of leaf blade: this project.

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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