| # The grass genera of the world |

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

### Aulonemia Goudot

Including Matudacalamus Mackawa

Excluding Cambajuva

Habit, vegetative morphology. Perennial; caespitose. The flowering culms leafy. Culms woody and persistent; branched above. Buds from which the primary culm branches arise consistently 1. Primary branches 1 (commonly), or 2–10, or 11–20 (very rarely); very rarely clumped. The branching dendroid. Culm leaves present (sometimes not differing from the vegetative ones). Culm leaf sheaths present, or absent; when present, deciduous, or persistent; conspicuously auriculate, or not conspicuously auriculate. Culm leaves with conspicuous blades (usually), or without conspicuous blades. Culm leaf blades linear, or lanceolate, or ovate, or triangular. Culm internodes hollow. Unicaespitose. Rhizomes pachymorph. Plants unarmed. Leaves not basally aggregated; with auricular setae, or without auricular setae. Leaf blades broad (always?); pseudopetiolate; cross veined, or without cross venation; disarticulating from the sheaths (where recorded); rolled in bud. Contra-ligule present, or absent.

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

Inflorescence. Inflorescence determinate; paniculate; open; without capillary branchlets (but these slender); spatheate. Spikelet-bearing axes paniculate; persistent. Spikelets not secund; pedicellate.

Female-fertile spikelets. Spikelets 35–40 mm long (probably underestimating the true range); linear (mostly), or lanceolate, or oblong; compressed laterally to not noticeably compressed; disarticulating above the glumes; disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret. Hairy callus absent.

Glumes two; very unequal; shorter than the adjacent lemmas; apically awned (both G1 and G2); similar. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets, or both distal and proximal to the female-fertile florets. The distal incomplete florets merely underdeveloped. The proximal incomplete florets 1; sterile. The proximal lemmas awned, or awnless (then mucronate); exceeded by the female-fertile lemmas; similar in texture to the female-fertile lemmas; not becoming indurated.

Female-fertile florets 3–12 (?- ‘few to many’). Lemmas similar in texture to the glumes; not becoming indurated; entire; blunt; mucronate, or awned. Awns when present, 1; apical; non-geniculate; hairless; much shorter than the body of the lemma to about as long as the body of the lemma. Lemmas non-carinate. Palea present; relatively long; not convolute; entire (pointed); awnless, without apical setae; not indurated; 2-keeled. Lodicules present; 3; free; membranous; ciliate; not toothed; heavily vascularized. Stamens 3. Anthers not penicillate; without an apically prolonged connective. Ovary apically hairy; without a conspicuous apical appendage. Styles fused. Stigmas 2.

Fruit, embryo and seedling. Fruit free from both lemma and palea; sub- fusiform, or ellipsoid; longitudinally grooved. Hilum long-linear. Embryo small.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent (but present as inconspicuous rings around the stomata adaxially). Long-cells similar in shape costally and intercostally (but the costals somewhat smaller); of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular (very regularly so); having markedly sinuous walls. Microhairs absent. Stomata common (abundant in broad bands adjoining the costal zones); 25.5–30 microns long. Subsidiaries consistently low to medium dome-shaped. Guard-cells slightly overlapped by the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs; silicified. Intercostal silica bodies narrowly saddle shaped, or tall-and-narrow. Macrohairs and prickles absent. Crown cells absent. Costal short-cells predominantly paired. Costal silica bodies saddle shaped (predominating, a tall-and-narrow version), or tall-and-narrow (a few).

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll without adaxial palisade; with arm cells (but these conspicuous only around the fusoids in the poor material seen); with fusoids. The fusoids external to the PBS. Leaf blade with distinct, prominent adaxial ribs (especially towards the middle). Midrib conspicuous; having complex vascularization. The lamina distinctly asymmetrical on either side of the midrib (one side being more conspicuously ribbed in the region near the midrib). Bulliforms present in discrete, regular adaxial groups; in simple fans (with a large, conspicuous group in each intercostal zone). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’ (every bundle with an I or an ‘anchor’). Sclerenchyma all associated with vascular bundles (in A. fulgor).

Classification. Watson & Dallwitz (1994): Bambusoideae; Bambusodae; Bambuseae. Soreng et al. (2015): Bambusoideae; Bambusodae; Bambuseae; Arthrostylidiinae. About 30 species.

Distribution, phytogeography, ecology. South America to Mexico and Costa Rica.

Glycophytic.

References, etc. Leaf anatomical: studied by us - A. fulgor McClure.

Illustrations. • Aulonemia queko: McClure, New World Bamboos (1973). • A. glaziovii and A. ramosissima (as A. glaziovii var. macroblephara): Camus (1913). • abbreviations for Camus (1913) figures. • A. effusa and Colanthelia distans (as Arundinaria spp.: Camus (1913). • Aulonemia fulgor, abaxial epidermis of leaf blade: this project. • Aulonemia fulgor, TS 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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