S5 - Glyceria Maxima Swamp Glycerietum maximae (Nowinski 1928) Hueck 1931 Emend. Krausch 1965

Summary

Synonymy

Glycerietum aquaticae Tansley 1911; Association à Scirpus lacustris et Glyceria aquatica Allorge 1922 p.p.; Scirpeto-Phragmitetum glyceriosum aquaticae Koch 1926; Glycerietum maximae and Glyceria reedswamp Tansley 1939; Scirpeto-Phragmitetum medioeuropaeum (Koch 1926) R.Tx. 1941 p.p.; Glyceria maxima communities Lambert 1947cp.p.; Glycerieto-Typhetum latifoliae Neuhäusl 1959 p.p.; Societie van Glyceria maxima Westhoff & den Held 1969; Glyceria maxima sociation Wheeler 1975a p.p.

Constant species

Glyceria maxima.

Physiognomy

The Glycerietum maximae is always overwhelmingly dominated by Glyceria maxima which forms a typically dense and luxuriant cover of leafy shoots, often more than 1 m long and sometimes attaining almost 2 m. The gross appearance of the vegetation is somewhat variable: the G. maxima plants may be firmly anchored and the shoots largely erect forming a tall emergent swamp; in other cases, stands occur as swinging masses of marginal ‘hover’, loosely attached below and with the shoots showing a marked tendency to lodge. Sometimes, stretches of this kind of Glycerietum may become detached to form free-floating islands of vegetation. Whatever its physiognomy, the community is typically very species-poor and pure stands are common.

Growth of the leafy aerial shoots of G. maxima begins early in the year and stands retain their characteristic bright, fresh green colour throughout the growing season as a succession of new shoots is produced (Lambert 1947c, Buttery & Lambert 1965, Westlake 1966). However, the erect shoots die back rapidly around November to produce a substantial mass of compact, black and slimy litter and so, unlike some swamp communities where the dominants are largely evergreen or where there is a large amount of standing dead material, the winter appearance of the vegetation here is very different from that of the growing season (Tansley 1939, Lambert 1947c, Westlake 1966). Decumbent shoots may remain winter-green, perhaps because of protection from frost or wind (Lambert 1947c).

Sub-communities

Glyceria maxima sub-community: Glyceria aquatica reedswamp Pallis 1911; Glyceria maxima floating reedswamp Lambert 1946; Glyceria society Spence 1964; Tall grass washlands Ratcliffe 1977 p.p.. This sub-community includes pure and species-poor stands in which G. maxima typically forms a very dense cover. Stands may be extensive and, as well as swamp or washland vegetation with erect plants, marginal and free-floating masses of ‘hover’ with many decumbent shoots are included here.