Grass Genera of the World

L. Watson and M. J. Dallwitz

Cynodon Rich.

From the Greek kuon (kun-, dog) and odous, odontos (tooth), perhaps alluding to the hard, conical, sharp basal buds on the rhizomes.

Including Capriola Adans., Dactilon Vill., Fibichia Koel.

Habit, vegetative morphology. Perennial; rhizomatous and stoloniferous (often sward-forming). Culms 4–60(–100) cm high; herbaceous. Culm nodes glabrous. Culm internodes hollow. Leaves not basally aggregated; non-auriculate. Leaf blades linear; narrow; setaceous, or not setaceous; flat, or folded; without abaxial multicellular glands; without cross venation; persistent; rolled in bud, or once-folded in bud; ligule present; a fringed membrane (very short), or a fringe of hairs.

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

Inflorescence. Inflorescence of spicate main branches; digitate, or subdigitate (sometimes in two or more closely spaced whorls). Primary inflorescence branches 2–20. Rachides flattened. Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; secund; biseriate.

Female-fertile spikelets. Spikelets 1.7–3 mm long; adaxial; compressed laterally; disarticulating above the glumes, or disarticulating between the glumes. Rachilla prolonged beyond the uppermost female-fertile floret, or terminated by a female-fertile floret (C. incompletus); hairless; the rachilla extension (when present) with incomplete florets (minute), or naked. Hairy callus absent.

Glumes two; very unequal to more or less equal; usually shorter than the spikelets, or about equalling the spikelets; shorter than the adjacent lemmas; dorsiventral to the rachis to lateral to the rachis; pointed; awnless; carinate; similar (narrow, lanceolate). Lower glume 1 nerved. Upper glume 1 nerved, or 1–3 nerved. Spikelets with female-fertile florets only (normally), or with incomplete florets. The incomplete florets (when present) distal to the female-fertile florets. The distal incomplete florets (if detectable) 1; merely underdeveloped (usually minute and greatly reduced). Spikelets without proximal incomplete florets.

Female-fertile florets 1. Lemmas similar in texture to the glumes to decidedly firmer than the glumes (firmly cartilaginous); not becoming indurated; entire; pointed, or blunt; awnless; ciliate on the keel and lateral nerves, usually glabrous on the flanks; carinate; 1–4 nerved. Palea present; relatively long; entire to apically notched; awnless, without apical setae; textured like the lemma; not indurated; 2-nerved. Lodicules present; free; fleshy; glabrous. Stamens 3. Anthers 0.6–1.7 mm long; not penicillate. Ovary glabrous. Styles free to their bases. Stigmas 2; red pigmented.

Fruit, embryo and seedling. Fruit free from both lemma and palea; small; ellipsoid; compressed laterally, or trigonous. Hilum short. Pericarp fused. Embryo large. Endosperm containing compound starch grains. Embryo with an epiblast; with a scutellar tail; with an elongated mesocotyl internode. Embryonic leaf margins meeting.

Seedling with a long mesocotyl; with a loose coleoptile. First seedling leaf with a well-developed lamina. The lamina broad; curved; 7–9 veined.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present; costal and intercostal. Intercostal papillae over-arching the stomata, or not over-arching the stomata; consisting of one symmetrical projection per cell to several per cell (usually as finger-like projections). 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 present; more or less spherical, or elongated; clearly two-celled, or ostensibly one-celled (occasionally); chloridoid-type (sometimes sunken). Microhair apical cell wall of similar thickness/rigidity to that of the basal cell. Microhairs 15–24 microns long. Microhair basal cells 6 microns long. Microhairs 10.5–15 microns wide at the septum. Microhair total length/width at septum 1.4–1.9. Microhair apical cells 9–16 microns long. Microhair apical cell/total length ratio 0.52–0.8. Stomata common; 18–21 microns long. Subsidiaries non-papillate; low dome-shaped and triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common, or absent or very rare; not paired (usually solitary); silicified, or not silicified. Intercostal silica bodies absent, or imperfectly developed; when present, tall-and-narrow. Costal short-cells conspicuously in long rows. Costal silica bodies present in alternate cell files of the costal zones; saddle shaped, or tall-and-narrow.

Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section open.

C4; biochemical type NAD–ME (2 species); XyMS+. PCR sheath outlines even. PCR sheaths of the primary vascular bundles interrupted; interrupted abaxially only. PCR sheath extensions absent. PCR cells without a suberised lamella. PCR cell chloroplasts elongated; with well developed grana; centripetal. Mesophyll with radiate chlorenchyma; traversed by columns of colourless mesophyll cells. Leaf blade adaxially flat. Midrib conspicuous; with one bundle only, or having a conventional arc of bundles. Bulliforms present in discrete, regular adaxial groups; associated with colourless mesophyll cells to form deeply-penetrating fans (these linked with the traversing colourless columns). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’, or nowhere forming ‘figures’. Sclerenchyma all associated with vascular bundles. The lamina margins with fibres.

Culm anatomy. Culm internode bundles in one or two rings.

Phytochemistry. Tissues of the culm bases with abundant starch. Leaves containing flavonoid sulphates (in some material of two species), or without flavonoid sulphates (3 species).

Cytology. Chromosome base number, x = 9 and 10. 2n = 16, 18, 27, 36, 40, and 54. 2, 3, 4, and 6 ploid. Chromosomes ‘small’. Nucleoli persistent.

Taxonomy. Chloridoideae; main chloridoid assemblage. Couch Grasses, Star Grasses.

Distribution, ecology, phytogeography. 10 species; tropical and subtropical. Commonly adventive. Mesophytic, or xerophytic; species of open habitats; halophytic and glycophytic. Disturbed and arable land, weedy and sandy places, seashores.

Holarctic, Paleotropical, Neotropical, Cape, Australian, and Antarctic. Boreal, Tethyan, and Madrean. African, Madagascan, Indomalesian, and Neocaledonian. Euro-Siberian and Eastern Asian. Mediterranean and Irano-Turanian. Saharo-Sindian, Sudano-Angolan, West African Rainforest, and Namib-Karoo. Indian, Indo-Chinese, Malesian, and Papuan. Caribbean, Venezuela and Surinam, Amazon, Central Brazilian, Pampas, and Andean. North and East Australian. Patagonian. European and Siberian. Sahelo-Sudanian, Somalo-Ethiopian, South Tropical African, and Kalaharian. Tropical North and East Australian and Temperate and South-Eastern Australian.

Hybrids. Intergeneric hybrids with ChlorisCynochloris Clifford & Everist: several species involved).

Rusts and smuts. Rusts — Puccinia. Taxonomically wide-ranging species: Puccinia graminis. Smuts from Ustilaginaceae. Ustilaginaceae — Sorosporium and Ustilago.

Economic importance. Significant weed species: C. dactylon (sometimes, in arable land), C. aethiopicus, C. incompletus, C. plectostachyus. Important native pasture species: C. dactylon, C. nlemfuensis, C. aethiopicus, C. plectostachyus. Lawns and/or playing fields: C. dactylon (Bermuda, Couch), C. transvaalensis etc.

References, etc. Leaf anatomical: this project.

Illustrations. • General aspect. • Vegetative shoot. Cynodon dactylon. • General aspect. Cynodon dactylon. • Inflorescence detail. Cynodon dactylon. • General aspect. Cynodon dactylon. • Spikelet. Cynodon dactylon. • Flower. Cynodon dactylon. • Abaxial epidermis of leaf blade. Cynodon dactylon. • Leaf blade transverse section. Cynodon dactylon. • Leaf blade transverse section. Cynodon dactylon. • Pollen antigens. • Pollen antigens. • Pollen antigens: cross-reactions against anti-Lolium serum. • Heat stable pollen antigens (allergens): cross-reactions against anti-Lolium serum. • Pollen antigens: cross-reactions against anti-Cynodon serum. • Pollen antigens: cross-reactions against anti-Zea serum. • Pollen antigens: cross-reactions against anti-Zea serum

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.’ 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).