| # The grass genera of the world |

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

### Limnas Trin.

Habit, vegetative morphology. Perennial. Culms 15–60 cm high; herbaceous. Leaves non-auriculate. Leaf blades linear; narrow; 0.6–4 mm wide; setaceous, or not setaceous; flat, or folded; not pseudopetiolate; without cross venation. Ligule present; an unfringed membrane; not truncate; 1–3 mm long.

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

Inflorescence. Inflorescence paniculate; fairly open (rather narrow, with short branchlets); espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.

Female-fertile spikelets. Spikelets 3–5 mm long; not noticeably compressed; falling with the glumes. Rachilla terminated by a female-fertile floret. Hairy callus present (beneath the glumes).

Glumes two; more or less equal; long relative to the adjacent lemmas; pointed (acute); awnless; carinate; similar (leathery). Lower glume 3 nerved. Upper glume 3 nerved. Spikelets with female-fertile florets only; without proximal incomplete florets.

Female-fertile florets 1. Lemmas similar in texture to the glumes (leathery); not becoming indurated; entire; pointed (acute); awned. Awns 1; median; dorsal; from well down the back; geniculate; entered by one vein. Lemmas hairless; non-carinate; without a germination flap; prominently 5 nerved. Palea present; conspicuous but relatively short (about 1/4 of the lemma length); 1-nerved; one-keeled. Lodicules present; 2; free; membranous; glabrous; not toothed; not or scarcely vascularized. Stamens 2, or 3. Anthers 2–2.5 mm long. Ovary apically glabrous. Styles fused. Stigmas 2.

Fruit, embryo and seedling. Fruit free from both lemma and palea.

Abaxial leaf blade epidermis. Costal/intercostal zonation lacking. Papillae absent. Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs absent. Stomata absent or very rare. Intercostal short-cells common; in cork/silica-cell pairs (many also in short rows, interspersed with prickles); silicified. Crown cells present (common, in addition to the numerous prickles). Costal short-cells neither distinctly grouped into long rows nor predominantly paired (in short rows and paired). Costal silica bodies rounded, tall-and-narrow, and crescentic; sharp-pointed (many having sharp points, including ‘tall, narrow’ and ‘round’ forms).

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade. Leaf blade with distinct, prominent adaxial ribs (and the leaf margins inrolling); with the ribs very irregular in sizes. Midrib conspicuous (by a slight abaxial keel); with one bundle only. Bulliforms not present in discrete, regular adaxial groups (bulliforms not apparent in the poor material seen). All the vascular bundles accompanied by sclerenchyma. Sclerenchyma not all bundle-associated. The ‘extra’ sclerenchyma in a continuous abaxial layer (constituting a lignified hypodermis).

Cytology. Chromosome base number, x = 7. 2n = 28. Chromosomes ‘large’.

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

Distribution, phytogeography, ecology. Central Asia to Northeast Siberia.

Mesophytic to xerophytic; glycophytic. Open woods and stony slopes.

References, etc. Leaf anatomical: studied bu us - L. stelleri Trin.

Special comments. Fruit data wanting.

Illustrations. • Limnas stelleri: Trinius (1823), Species Graminum 1.

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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