FESTUCA GLAUCA LAM. AND THE VAR. CAESIA (SM.) K. RICHT BLUE OR GREY FESCUE P . J. O . TRIST
IN spite of intensive searches on the poor open grassland heaths at Deadman's Grave, Icklingham Plains, and along the Seven Tree Road all in the parish of Icklingham, Festuca glauca has only been found by the writer in two places in the Suffolk Breckland. It is frequent on Foxhole Heath and on the roadside verge and is localised along a few yards of the roadside bank in Lords Walk Road, both sites being in the parish of Eriswell. Hind (1889) gives the earliest record by Sir J. Cullum (1773) and the only West Suffolk record is for Mildenhall. Sir James E. Smith (1759-1828) spent the last thirty years of his life in Norfolk and frequently visited Sir Thomas Cullum in Bury St. Edmunds. In Hb. Smith at the Linnean Society's rooms in London, there are specimens labelled Festuca caesia from "heaths about Bury 1804" and in Hb. Kew another of Smith's specimens is named Festuca glauca. Lowe (1868) records Festuca ovitia var. caesia. F. glauca was first described by Hackel (1868) who treated F. caesia Sm. as a sub-variety of F. glauca. The modern floras have continued to give F. glauca Lam. and F. glauca var. caesia Sm. as separate plants. The var. caesia has been recognised as a very much smaller plant with distinctly curved leaves within the ränge 1 • 5-7 • 0 cm. in length and 0-2-0-4 mm. in width and grey-blue in colour. By contrast F. glauca is found with leaves 8-22 cm. in length and 0-3-0-8 mm. in width. The colour is a glaucous green and there is an absence of the typical curve found in the var. caesia. The writer started field observations on these two plants in 1963 and transplanted both into a garden in Bury St. Edmunds. It was subsequently seen that the small plants of var. caesia responded to improved conditions of fertility in the garden and grew identical to F. glauca. Leaf length and width increased and the former distinct leaf curve became absent. Many measurements of all parts of both of these plants were taken and it was found that there was no significant difference in the floral characters. The Breckland has a slightly lower rainfall than the county average. The soil ranges from a coarse sand to a chalk loam sand and the texture is very open with a low organic matter percentage. It is, therefore, very subject to drought within a short space of time. F. glauca is always found in a closed sward, which in spite of a greater moisture demand also helps to prevent a rapid loss of moisture from the surface. The var. caesia is not found in this
Suffolk Natural History, Vol. 75, Part 5
closed Community but in open areas. It is, therefore, trying to survive in a soil with an extremely low nutritional status which suffers a rapid loss of moisture. When this plant is moved to a soil where moisture and plant food is more readily available, its mode of growth is comparable with F. glauca. It is concluded that the grass named Festuca glauca var. caesia (Sm.) K. Rieht is none other than a plant of Festuca glauca Lam. growing under unfavourable conditions. A fĂźll account of the habitat and conclusions on this study will be found in a future volume of Watsonia Journal and Proc. Bot. Soc. Br. Isl. P.J.
O. Trist, O.B.E., B.A.Hons., M.R.A.C., F.L.S., Street, Bury St. Edmunds, Suffolk.