1907. Praegkr. — Phanerogams, &c, of Lambay. 95 



good admixture of heath plants, such as Viola sylvatica, Lotus 

 comiculatus, Potentilla 7orme?itilla, Sedum angliaim, Galium 

 saxatite, Veronica officinalis, Tencrium Scorodo?iia. 



The Rush Association. 



The course of streamlets at Raven's Well and above Fresh- 

 water Bay is marked by a dense even growth of Rushes, and 

 it is interesting to note that the species which almost mono- 

 polizes these places is one which is by no means generally 

 common in county Dublin — namely, Ju?icus obtusiflorus. 

 J. glaucus and /. effusus are also present in smaller quantity. 

 The ground here is mostly very wet and mossy, the prevailing 

 mosses being Hypnum aipressifotme and H. cuspidat7im. 

 Chara vulgaris grows mixed with them. Other species which 

 find here their head quarters on Lambay are Me?itha hirstita, 

 Apiu7}i modifloruni) Ranunculus acris and R. Flam??iula, Spircea 

 Ulmaria, Carex flava, A?iagallis te?iella> &c. 



The presence of Juiuus obtusiflorus, J. glaztcus, and Chara 

 vulga?is in the marshy places points to the presence of lim3 r 

 water, and further evidence of this is seen in the deposits of 

 calc-sinter in the roofs of caves and on cliffs where streamlets 

 empty themselves into the sea — notably at the foot of the 

 Freshwater stream. This lime is no doubt derived from the 

 drift, though its quantity is greater than the distribution and 

 nature of the Boulder-clay might lead one to expect. 



The Desert Association. 



One of the most remarkable features of Lambay is the 

 occurrence in the south-east of considerable patches of almost 

 bare crumbling rock and soil, on which a flora of desert type 

 maintains a precarious existence (Plate 23.) In these places soil 

 is practically absent ; the volcanic rock shows through, or is 

 covered by the merest skin of decayed fragments, mixed with 

 a little dry humus. The peculiar type of vegetation which 

 here prevails is the result of deficient moisture. The leading 

 plant of these " deserts " is the English Stonecrop (Sedum 

 anglicum), which grows in profusion. At flowering time the 

 sun has tinted the leaves and stems a brilliant red, which can 

 be seen from a great distance, and the numerous star-like 



