Cynodon dactylon var. dactylon is a highly variable perennial C4 grass widely grown in many tropical and warm temperate regions of the world (DiTomaso and Healy 2007). Hundreds of cultivars have been developed for a wide range of uses, such as durable turf for lawns, athletic fields, golf courses, soil stabilization, wildlife forage, livestock pasture, and hay (Alderson and Sharp 1995; USDA-AMS 2023c; USDA-NRCS 2020).

Plants can rapidly colonize new areas via seeds or rhizome and stolon fragments forming dense mats (DiTomaso and Healy 2007; Rojas-Sandoval and Acevedo-Rodríguez 2014). Due to a vigorous creeping habit, and the ability to quickly recover after fire, tolerate flooding, and prolonged drought, C. d. var. dactylon has become a significant weed pest in many places around the world (Rojas-Sandoval and Acevedo-Rodríguez 2014).

Unintentional dispersal of seeds or stolon and rhizome fragments can occur by flooding, irrigation, contaminated agricultural and landscape maintenance equipment, movement of hay bales, and by animals ingesting and passing the seeds in manure (Di Tomaso and Healy 2007; Rojas-Sandoval and Acevedo-Rodríguez 2014). Seeds can also be spread as contaminants in commercial seed lots of agricultural and vegetable seeds.

Sensitive individuals may develop dermatitis following contact with the plants and C. dactylon pollen is a common cause of hay fever (Fuller and McClintock 1986). In the United States, reports of photosensitization, neurological problems, and symptoms of mold or fungal toxicity have occurred in cattle grazing on C. dactylon. (Fuller and McClintock 1986; Di Tomaso and Healy 2007).

Cynodon dactylon is listed as invasive in Australia, Indonesia, Singapore, Cambodia, Vietnam, Mexico, Costa Rica, Puerto Rico, Chile, Colombia, Uruguay, Argentina, Brazil, on many Pacific islands, and elsewhere (Rojas-Sandoval and Acevedo-Rodríguez 2014). It is also classified as a noxious weed seed in many US states (USDA-AMS 2023b). As an invasive plant, C. dactylon has the potential to diminish crop yield by out competing crop plants, to increase cost of crop production (e.g., herbicides, manual labor), and to threaten native species by competing for resources, strangling native plants, and altering plant community composition (Rojas-Sandoval and Acevedo-Rodríguez 2014).

The species C. dactylon is divided into six botanical varieties (Harlan and de Wet 1969). In addition to C. d. var. dactylon, the five other botanical varieties include:

C.d. var. afghanicus J. R. Harlan & de Wet plants are similar to other botanical varieties of C. dactylon except they do not produce rhizomes or produce only very short rhizome-like structures at the crown of the plant (Harlan and de Wet 1969). This variety is limited in known distribution to the steppes of Afghanistan (de Wet and Harlan 1970; USDA-ARS-NPGS 2023).

C. d. var. aridus Harland & de Wet (giant bermudagrass; USDA-ARS-NPGS 2023) is described as a large, robust plant, blueish-green in colour, producing deep and fast spreading rhizomes, as well as developing remarkably long, slender, and fast-growing stolons with leafy tips (Harlan and de Wet 1969), and lacking pubescence (Alderson and Sharp 1995). This variety is native to South Africa, Zambia, Tanzania, Israel, India, and Sri Lanka (USDA-ARS-NPGS 2023). Its introduction and spread are limited elsewhere (Harlan and de Wet 1969). Seeds of this variety are commercially available and are sometimes sold in mixtures with seeds of C. d. var. dactylon. This variety is used for fodder, forage, erosion control, lawn, and turf (Markle et al. 1998).

C. d. var. coursii (A. Camus) J. R. Harlan & de Wet does not produce rhizomes, the robust stolons and stems produce plants 40 to 50 cm tall, leaves on the upper stems are pressed tightly against the stem and are bunched at the tip (Harlan and de Wet 1969; de Wet and Harlan 1970). This variety is endemic to the highlands of Madagascar (Harlan and de Wet 1969).

C. d. var. elegans Rendle plants are described as rhizomatous, forming a loose mat of stems lying on the ground or rising in an arc, tips of the stolons are scaly, and plants are green in colour (Harlan and de Wet 1969). This variety is native to Angola, Mozambique, Zambia, Zimbabwe, Namibia, and South Africa (USDA-ARS-NPGS 2023).

C. d. var. polevansii (Stent) J. R. Harlan & de Wet plants are dark green coloured, the stolons are branched with short internodes that form a dense turf with stiff upright leaves (Harlan and de Wet 1969). This variety is endemic to saline areas in the North-West Province of South Africa (Harlan and de Wet 1969; de Wet and Harlan 1970).

Cynodon dactylon var. dactylon can hybridize, either naturally or experimentally, with other botanical varieties of C. dactylon and other Cynodon species (Harlan and de Wet 1969; de Wet and Harlan 1970).