| # The grass genera of the world |

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

### Colpodium Trin.

From the Greek kolpos (a bay or gulf), re emarginate lemmas (?).

Including Paracolpodium Tsvelev., Keniochloa Melderis

Excluding Catabrosella, Hyalopoa

Habit, vegetative morphology. Perennial; rhizomatous, or stoloniferous, or caespitose, or decumbent. Culms 10–30 cm high; herbaceous; unbranched above. Leaves non-auriculate. Sheath margins joined to free. Leaf blades flat; not pseudopetiolate; without cross venation. Ligule an unfringed membrane; truncate, or not truncate; 3 mm long.

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

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

Female-fertile spikelets. Spikelets 2–8 mm long; compressed laterally to not noticeably compressed; disarticulating above the glumes. Rachilla prolonged beyond the uppermost female-fertile floret, or terminated by a female-fertile floret; the rachilla extension when present, with incomplete florets, or naked. Hairy callus absent. Callus short; blunt.

Glumes two; relatively large; more or less equal; shorter than the adjacent lemmas, or long relative to the adjacent lemmas; pointed, or not pointed (broadly rounded or erose); awnless; non-carinate; similar. Lower glume longer than half length of lowest lemma; 1 nerved. Upper glume 1–3 nerved. Spikelets with female-fertile florets only, or with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped; awnless. Spikelets without proximal incomplete florets.

Female-fertile florets 1. Lemmas with several teeth; similar in texture to the glumes to decidedly firmer than the glumes (thinly membranous, the tip hyaline); not becoming indurated; incised; 3–5 lobed (toothed); not deeply cleft; awnless; hairy, or hairless; carinate to non-carinate; without a germination flap; 3–5 nerved. Palea present; relatively long; 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; glabrous; toothed; not or scarcely vascularized. Stamens 3. Anthers 1.5–3.5 mm long. Ovary apically glabrous. Styles free to their bases. Stigmas 2; white.

Fruit, embryo and seedling. Fruit free from both lemma and palea; medium sized. Hilum short (oblong). Embryo small.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present (in Keniochloa), or absent; when present, costal and intercostal. Intercostal papillae over-arching the stomata; consisting of one oblique swelling per cell. Long-cells similar in shape costally and intercostally, or markedly different in shape costally and intercostally; of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular, or fusiform; having straight or only gently undulating walls. Microhairs absent. Stomata common; 22.5–27 microns long (in Keniochloa), or 39–41 microns long (in Paracolpodium). Subsidiaries non-papillate; parallel-sided, or parallel-sided and dome-shaped (in Keniochloa). Guard-cells overlapped by the interstomatals. Intercostal short-cells common, or absent or very rare; not paired; not silicified. Costal short-cells neither distinctly grouped into long rows nor predominantly paired, or no costal short-cells in Paracolpodium altaicum. Costal silica bodies horizontally-elongated smooth, or rounded, or tall-and-narrow, or crescentic, or .

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma. Midrib with one bundle only. Bulliforms present in discrete, regular adaxial groups; in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present. Sclerenchyma all associated with vascular bundles.

Cytology. Chromosome base number, x = 2. 2n = 4, or 8 (in Keniochloa), or 28 (C. colchicum, Paracolpodium). 2 ploid, or 4 ploid, or 14 ploid. Chromosomes ‘large’.

Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Poeae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Coleanthinae. Sensu stricto 3 species (?).

Distribution, phytogeography, ecology. High altitude North temperate.

Montane.

References, etc. Morphological/taxonomic: Bor 1970. Leaf anatomical: studied by us - C. altaicum Trin. (= Paracolpodium), C. chionogeiton Pilg. (= Keinochloa).

Illustrations. • Colpodium altaicum: Ledebour, Icones Plantarum 3 (1831). • Colpodium fibrosum: Bor, Flora of Iraq (1968). • C. hedbergii: Gibbs Russell et al., 1990.

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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