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The grass genera of the world

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

Dinochloa Buese

From the Greek deinos (fearful, marvellous) and chloa (a grass), alluding to size.

Excluding Melocalamus

Habit, vegetative morphology. Perennial. The flowering culms leafy. Culms 1000–3000 cm high (sympodial, zigzag); woody and persistent; to 5 cm in diameter; scandent (high-climbing); branched above. Primary branches 4–20. The branching dendroid. Culm leaf sheaths present; deciduous (usually), or persistent; leaving a persisten girdle (commonly), or not leaving a persistent girdle; conspicuously auriculate, or not conspicuously auriculate. Culm leaves with conspicuous blades. Culm leaf blades linear, or lanceolate, or ovate, or triangular. Culm internodes solid, or hollow (flexuous). Plants conspicuously armed (thorny), or unarmed (but the culms rough). Leaves not basally aggregated; auriculate (with bristles adjoining). Leaf blades broad; 25–100 mm wide (by 8 to 45 cm long); not cordate, not sagittate (bases cuneate); pseudopetiolate; cross veined; disarticulating from the sheaths; rolled in bud. Ligule a fringed membrane (‘shortly ciliate’). Contra-ligule absent.

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

Inflorescence. Inflorescence indeterminate; with pseudospikelets; a large fan of slender, leafless inflorescence branches up to 3 m long, with spikelets in pairs and groups at their nodes; spatheate; a complex of ‘partial inflorescences’ and intervening foliar organs (but without foliage leaves). Spikelet-bearing axes paniculate; persistent. Spikelets not secund (the spikelet pairs and clusters alternate); pedicellate; consistently in ‘long-and-short’ combinations, or not in distinct ‘long-and-short’ combinations. The ‘shorter’ spikelets hermaphrodite. The ‘longer’ spikelets hermaphrodite.

Female-fertile spikelets. Spikelets unconventional; 2–4(–5) mm long; oblong (commonly), or elliptic, or lanceolate; slightly compressed laterally; falling with the glumes. Rachilla terminated by a female-fertile floret.

Glumes two, or several (2–3); very unequal (G1 smaller); shorter than the adjacent lemmas; free; conspicuously ventricose; not pointed (broad, obtuse, convolute); awnless; similar. Lower glume 9 nerved (in material seen). Upper glume 9 nerved (in material seen). Spikelets with female-fertile florets only.

Female-fertile florets 1. Lemmas similar in texture to the glumes; mucronate (or mucronulate); 9 nerved (in the species seen). Palea present (glabrous); relatively long (longer than lemma); convolute around the flower (D. palawenensis), or not convolute (nearly always); apically notched (slightly 2-pointed, the points touching); awnless, without apical setae (mucronate); thinner than the lemma; not indurated; several nerved (11 in the species seen); keel-less. Lodicules absent. Stamens 6 (short). Anthers 4 mm long; penicillate, or not penicillate; with the connective apically prolonged (acute). Ovary apically glabrous; with a conspicuous apical appendage, or without a conspicuous apical appendage. The appendage when present, broadly conical, fleshy. Styles fused (into a single style with a wide solid base). Stigmas 3 (slightly plumose).

Fruit, embryo and seedling. Fruit subglobose (spheroidal); not noticeably compressed. Pericarp thin, or fleshy (i.e. pericarp sometimes thick, wrinkled when dry). Embryo large (1/2 to 1/3 as long as fruit). Seed ‘non-endospermic’.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present; intercostal. Intercostal papillae over-arching the stomata; several per cell (variously shaped, sometimes exclusively forming rings over and around the stomata). Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular; having markedly sinuous walls (thin). Microhairs present; clearly two-celled, or uniseriate (occasionally 3-celled); panicoid-type (rather variable in form); (60–)66–75(–78) microns long (in D. pubivanea); 5.4–19.5 microns wide at the septum. Microhair total length/width at septum 6.7–14.4 (i.e. very variable, in D. pubivanea). Microhair apical cells (31.5–)40.5–42(–51) microns long. Microhair apical cell/total length ratio 0.53–0.65. Stomata common (obscured by papillae); 28.5–30 microns long (in D. pubivanea). Subsidiaries non-papillate. Guard-cells overlapped by the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs; silicified. Intercostal silica bodies tall-and-narrow. Costal short-cells conspicuously in long rows, or predominantly paired, or neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies saddle shaped, or tall-and-narrow, or crescentic, or oryzoid.

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; with adaxial palisade; with arm cells; with fusoids (very large). The fusoids external to the PBS. Leaf blade adaxially flat. Midrib conspicuous; having complex vascularization. Bulliforms present in discrete, regular adaxial groups; in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’ (most bundles).

Cytology. Chromosome base number, x = 12. 2n = 72.

Classification. Watson & Dallwitz (1994): Bambusoideae; Bambusodae; Bambuseae. Soreng et al. (2015): Bambusoideae; Bambusodae; Bambuseae; Bambusinae. About 25 species.

Distribution, phytogeography, ecology. Southeast Asia, Indo-Malaya.

References, etc. Leaf anatomical: Metcalfe 1960; studied by us - D. pubiramea Gamble.

Illustrations. • D. acutiflora (as Schizostachyum), D. scandens, D. andamanica, D. luconiae (as ciliata): 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: 11th December 2017.’.