| # The grass genera of the world |

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

### Gigantochloa Kurtz ex Munro

From the Greek gigas (giant) and chloa (grass).

~ Dendrocalamus

Habit, vegetative morphology. Arborescent perennial; sympodial, caespitose. The flowering culms leafless, or leafy. Culms 300–3000 cm high; woody and persistent; to 2–14 cm in diameter; scandent, or not scandent; branched above. Buds from which the primary culm branches arise in the few cases where recorded, 1. Primary branches (1–)4–20. The branching dendroid. Culm leaf sheaths present; deciduous, or persistent; leaving a persisten girdle (occasionally), or not leaving a persistent girdle; nearly always conspicuously auriculate. Culm leaves with conspicuous blades. Culm leaf blades lanceolate, or ovate, or triangular. Culm internodes hollow. Rhizomes pachymorph. Plants unarmed. Leaves not basally aggregated; auriculate (low sheath auricles, bristly or not); with auricular setae, or without auricular setae. Leaf blades broad (and the leaves rather large); pseudopetiolate; cross veined; demarcated, disarticulating from the sheaths, or persistent; rolled in bud. Ligule an unfringed membrane, or a fringed membrane. Contra-ligule present (nearly always), or absent (e.g., G. felix).

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant (?), or all alike in sexuality.

Inflorescence. Inflorescence indeterminate; with pseudospikelets (the spikelets with ‘several basal bracts and glumes’); of paniculate pseudo-inflorescences, in alternate clusters along leafless branches; spatheate; a complex of ‘partial inflorescences’ and intervening foliar organs. Spikelet-bearing axes paniculate; persistent. Spikelets not secund.

Female-fertile spikelets. Spikelets unconventional; 9–50 mm long; lanceolate (mostly), or ovate, or linear (e.g., G. macrostachya); compressed laterally; falling with the glumes (‘spikelets falling whole’). Rachilla prolonged beyond the uppermost female-fertile floret.

Glumes present; two to several; shorter than the adjacent lemmas; awnless (mucronate); similar. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets, or both distal and proximal to the female-fertile florets (if upper ‘glumes’ (which may subtend young spikelets) are regarded as proximal lemmas). The distal incomplete florets merely underdeveloped. Spikelets with proximal incomplete florets. The proximal lemmas awnless (mucronate); exceeded by the female-fertile lemmas.

Female-fertile florets 2–5. Lemmas increasing in length acropetally; mucronate (or at least apiculate); with more than 5 nerves. Palea present (much narrower than lemmas); relatively long, or conspicuous but relatively short; not convolute; entire (in upper florets), or apically notched (in lower florets); awnless, without apical setae; thinner than the lemma (thin, translucent); not indurated; several nerved (2–5 between the keels, 0–3 on either side); 2-keeled. Lodicules usually absent. Stamens 6; monadelphous (the tube longer than the palea). Anthers 4–9 mm long; penicillate; with the connective apically prolonged. Ovary apically hairy; with a conspicuous apical appendage, or without a conspicuous apical appendage. The appendage when present, broadly conical, fleshy. Styles fused (into one long style, not rigid, not hollow). Stigmas 1(–3).

Fruit, embryo and seedling. Fruit narrowly fusiform; longitudinally grooved; not noticeably compressed; with hairs confined to a terminal tuft. Hilum long-linear. Pericarp thin. Embryo small.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present. Intercostal papillae over-arching the stomata; several per cell (of various shapes). Mid-intercostal long-cells having markedly sinuous walls. Microhairs present; panicoid-type. Stomata common (obscured by papillae). Intercostal short-cells common; in cork/silica-cell pairs; silicified. Intercostal silica bodies tall-and-narrow. Costal short-cells conspicuously in long rows (by amalgamation of pairs), or predominantly paired. Costal silica bodies saddle shaped.

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll traversed by columns of colourless mesophyll cells; with arm cells; with fusoids. Leaf blade with distinct, prominent adaxial ribs; with the ribs more or less constant in size. Midrib conspicuous; having complex vascularization. Bulliforms present in discrete, regular adaxial groups; associated with colourless mesophyll cells to form deeply-penetrating fans (these linking with traversing colourless cells). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present. Sclerenchyma all associated with vascular bundles.

Phytochemistry. Leaves without flavonoid sulphates.

Cytology. Chromosome base number, x = 12. 2n = 70 and 72. 6 ploid.

Classification. Watson & Dallwitz (1994): Bambusoideae; Bambusodae; Bambuseae. Soreng et al. (2015): Bambusoideae; Bambusodae; Bambuseae; Bambusinae. 20 species.

Distribution, phytogeography, ecology. Indomalayan.

Forests.

Economic aspects. Culms of G. apus, G. maxima, G. nigrociliata etc. used for house construction, as well as for furniture, household appliances etc.

References, etc. Leaf anatomical: Metcalfe 1960.

Illustrations. • Gigantochloa albociliata, G. parvifolia and G. densa (as Oxytenanthera 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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