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; an unfringed membrane; truncate, or not truncate; 3 mm long.
Reproductive organization. Plants bisexual, 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 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’.
Taxonomy. Pooideae; Poodae; Poeae.
Distribution, ecology, phytogeography. Sensu stricto 3 species (?); high altitude North temperate. Montane.
Holarctic and Paleotropical. Boreal and Tethyan. African and Indomalesian. Arctic and Subarctic. Irano-Turanian. Sudano-Angolan. Indian. Somalo-Ethiopian and South Tropical African.
References, etc. Morphological/taxonomic: Bor 1970. Leaf anatomical: this project.
Illustrations. • General aspect
Cite this publication as: Watson, L., and Dallwitz, M. J. (1992 onwards). ‘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.’ http://biodiversity.uno.edu/delta/. Version: 18th August 1999. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993 onwards, 1998), and Watson and Dallwitz (1994), and Watson, Dallwitz, and Johnston (1986) should also be cited (see References).
