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The grass genera of the world

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

Aniselytron Merr.

~ Calamagrostis

Including Aulacolepis Hack., Neoaulacolepis Rauschert

Habit, vegetative morphology. Perennial; caespitose, or decumbent. Culms 40–100 cm high; herbaceous; unbranched above. Young shoots extravaginal. Leaves not basally aggregated; non-auriculate. Leaf blades linear; broad to narrow; 2.3–21 mm wide; flat; not pseudopetiolate; persistent. Ligule an unfringed membrane (sometimes ciliolate); truncate to not truncate (collar shaped to triangular); 0.3–7.5 mm long.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets; exposed-cleistogamous, or chasmogamous (?).

Inflorescence. Inflorescence paniculate; open; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate; not in distinct ‘long-and-short’ combinations.

Female-fertile spikelets. Spikelets 2.4–4.6 mm long; at least somewhat compressed laterally; disarticulating above the glumes. Rachilla prolonged beyond the uppermost female-fertile floret; hairless (glabrous); the rachilla extension naked. Hairy callus present. Callus short; blunt.

Glumes two; relatively large; very unequal (the G1 being very small or rudimentary); shorter than the spikelets; shorter than the adjacent lemmas; hairless; glabrous to scabrous; pointed; awnless; carinate; very dissimilar (the G1 much shorter, sometimes a mere scale). Lower glume 0 nerved, or 1 nerved. Upper glume 1 nerved, or 3 nerved. Spikelets with female-fertile florets only.

Female-fertile florets 1. Lemmas acute; decidedly firmer than the glumes (leathery); not becoming indurated; entire; pointed; awnless to mucronate (attenuate, sometimes into a hooked or filiform mucro); hairless; scabrous; carinate; without a germination flap; 5 nerved. Palea present; relatively long; entire (narrow); awnless, without apical setae; 2-nerved; 2-keeled (the rachilla prolongation residing between the keels). Palea keels wingless. Lodicules present; 2; free; membranous; glabrous; toothed, or not toothed; not or scarcely vascularized. Stamens 3. Anthers 0.6–2 mm long (yellow); not penicillate; without an apically prolonged connective. Ovary apically glabrous. Styles free to their bases. Stigmas 2.

Fruit, embryo and seedling. Fruit free from both lemma and palea; small (1.25–2 mm long); compressed laterally, or not noticeably compressed. Hilum short. Embryo small. Endosperm containing compound starch grains.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally; differing markedly in wall thickness costally and intercostally (the costals thicker walled). Mid-intercostal long-cells fusiform; having straight or only gently undulating walls (to very minutely so). Microhairs absent. Stomata absent or very rare. Intercostal short-cells fairly common (adjoining the bases of adjacent prickles); not paired; not silicified. With numerous bulbous-based prickles. Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies horizontally-elongated smooth, or horizontally-elongated crenate/sinuous (a few being slightly sinuous).

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade. Leaf blade with distinct, prominent adaxial ribs to ‘nodular’ in section (the ribs round, low-topped); with the ribs more or less constant in size. Midrib conspicuous (via a large bundle and a slight abaxial keel); with one bundle only, or having a conventional arc of bundles (depending on interpretation - there being a small bundle on each side and fairly close to the large median). Bulliforms present in discrete, regular adaxial groups (in the broad furrows); in simple fans (the fans broad). Many of the smallest vascular bundles unaccompanied by sclerenchyma (and others with only negligible ‘strands’). Combined sclerenchyma girders present (with the midrib and the other primaries); forming ‘figures’ (the median midrib bundle). Sclerenchyma all associated with vascular bundles.

Cytology. Chromosome base number, x = 7; 6 ploid.

Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Aveneae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Poinae. 2 species.

Distribution, phytogeography, ecology. Sikkim, northern Burma, China, Japan, Taiwan, Luzon, Sabah, northern Sumatra.

Mesophytic; shade species. Montane.

References, etc. Morphological/taxonomic: Korthoff and Veldkamp 1984. Leaf anatomical: this project.

Illustrations. • A. treutleri, as Deyeuxia (Hook. Ic. Pl., (1895)


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: 13th November 2017. delta-intkey.com/grass’.

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