NOTE ON ACCOMMODATION IN POLYGALA VULGARIS 349 



All the leaves are of the light green, herbaceous type, pro- 

 duced by the shading of surrounding grasses. 



The more branched forms, i.e., with more numerous branches 

 in each rosette, spread out their branches, pressing the grasses 

 away and obtaining access to light and air for themselves. 



The bog form (fig. 2) occurs on the drier parts of an old peat 

 bog. Turf has been cut and deep trenches formed. These have 

 filled up with water and the whole area re-colonized by plants, so 

 that the whole is almost levelled and path-way can only be found 

 along the tops of old banks. 



The wet parts contain Menyanthes trifoliate,, Equisetum limo- 

 sam, Hypericum pulchrum, Sphagnum spp., Juncus conglomerates 

 and articulatus, Eriophorum angustifolium, &c. The drier parts 

 contain Eriophorum vaginatum, Oxycoccus quaclripetala, Nar- 

 thecium Ossifragum, Erica Tetralix, E. cinerea, Calluna vulgaris, 

 Molinia ccerulea, Scirpus ccespitosus, Nardus striata, Vaccinium 

 Myrtillus, and Ulex europceus. Here, growing through the wet 

 tufts of Sphagnum, drier tufts of Juncus conglomerates and bushes 

 of Ulex europtzus, the Poly gala vulgaris is found. 



Its root system is similar to that of the meadow form, though 

 exceeding it in average length by 3 cm. (average of twenty 

 specimens). It is entwined among the lower layers of the still 

 living Sphagnum and the roots of grasses, never penetrating 

 deeply. 



Almost immediately above the root, the stem branches re- 

 peatedly give rise to 3-8 thin, etiolated shoots, with small, 

 ovate, often subopposite leaves. These shoots are supported by 

 the grasses and shoots through which they grow till they reach 

 air and light. Here they again branch, forming the rosettes of 

 small, ovate leaves, as in the meadow form, but with larger 

 lanceolate leaves scattered among them. Above this rosette, 

 which rests on cross branches of Ulex or the upper layers of 

 grass, the plant entirely resembles the meadow form, except that 

 the specimens which are not shaded by surrounding vegetation 

 develop a distinct purple tint on stem and leaves, especially on 

 midrib and leaf margins. In some lower leaves the chlorophyl is 

 completely masked by the purple coloration. 



The flowers resemble those of the meadow form, except that 

 the latter have more chlorophyl coloration in their three smaller 

 sepals. 



In the bog form these sepals are slightly paler than the two 

 wings, but are only faintly tinged with green in the very young 

 stage. 



Twenty plants were examined and measured in the field, and 

 ten more in the laboratory ; from these thirty bog forms the 

 following measurements were obtained : — 



Average length of shoot .... 

 Number of shoots to each plant 

 Distance of point of branching from base 

 Distance of rosette from base . 

 Average length of main root 



