Dactylis glomerata L.

Abstract

A coarse, tussock-forming, perennial grass with the culms erect or spreading and the vegetative shoots considerably flattened. Sheaths of the leaves entire; ligules large and sometimes slightly hairy at the back and serrate at the apex. Blades usually glaucous, without auricles, fairly broad, folded in the shoot and strongly keeled; leaf margins minutely toothed; the teeth can be numerous and well deyeloped (Christoph 1925, Bulacevic 1934, Lackamp 1955). Leaves on the panicle stem tend to increase in length from the flag-leaf downwards and may also show a slight increase in width. Stem solid only in the young sheath; as the culm matures the lumen increases both transversely and longitudinally. Panicles stiffly erect, with branches close together or at least the lowermost distant. Spikelets with 2-5 flowers, almost sessile and arranged in dense, one-sided, ovate masses. Glumes and lemmas ovate-lanceolate, acute, usually with stiff bristles along the keel. Lemmas furnished with a short, stiff awn. The plant is usually glabrous, but forms showing varying degrees of hairiness are found occasionally among the populations examined at Aberystwyth. This character is not correlated with any special habitat conditions (Stapledon 1928). This type (var. utbescens Opiz) has also been found in Hampshire (C. E. Hubbard). Anthocyanin is fairly generally present in young seedlings especially on the sheaths, but in mature plants the colour is not normally obvious, except in early summer on the culm sheaths, nodes and glumes. The intensity of colour on the glumes can be such as to give the panicle a distinctly purple appearance and this colour is more intense in a dry year (C. E. Hubbard). Plants which are free from anthocyanin also occur. D. glomerata is regarded as the only British species of the genus. It is very variable: Domin (1943)* gives 160 named infra-specific variants, and C. E. Hubbard says there are at least 200 names applying to taxa under D. glomerata L. (sensu lato) scattered throughout European botanical literature. A number of ecotypes have been described varying between the form with a spreading prostrate growth habit to one which is narrowly erect (Stapledon 1928). The former types tend to be most common in heavily grazed pastures, while the taller forms predominate in habitats which are only occasionally grazed or mown, as for example on or near hedge banks, and in waste places. The leaves range in colour from yellow-green to blue-green, but yellow and variegated forms are met with, especially as a result of inbreeding. Such types have been used as ornamental plants, e.g. var. fiava Mort., a form with yellow or golden leaves and inflorescences; variegated types 'a'treo-variegatis', 'albo-variegatis' and 'aureo-lineatis', depending on