1917.] Ecology of the Nilgiri and Pulney Highland Plateau. 257 



Blumea hieracifolia, DC grows near streams, often almost in 

 the water and has thick leaves ; while B. neilgherrensis which 

 grows on the open downs where the soil is often very dry, has 

 thin aromatic and slighthr woolly leaves; and another species, 

 not identified, which occurs on the very wettest spots on the 

 downs, has very excessively hairy leaves. Again Exacum atro- 

 purpureum, Bedd., one of the Gentianaceae, grows especially 

 near running water, on rocks near waterfalls and in the beds of 

 streams, and has leaves much thicker than the closely related 

 E. Wightianum, Arnott, which grows on the open hill sides. It 

 may be that plants which are exposed to the greatest alterna- 

 tion of wet and dryness, as in situations near streams which 

 certainly dry up in the dry months from January to April, 

 have more need of xerophytic adaptation than those which 

 grow in soil that is never so wet and never drier. Otherwise it 

 is certainly curious that there should be this contradiction of so 



universal a rule. 



Coming now to the grassy hill sides where the soil is deep 

 enough to allow of a rich and varied flora as soon as the summer 

 rains begin : the commonest grasses are the purple Ischaenium 

 ciliare, Retz., the silky auburn-coloured Pollinia phaeothrix, 

 Hack., a coarse hairv-leafed Arundinella, and the Stork's head, 

 Heteropogon ( Andropogon) contortus, Beauv. The smaller herbs 

 have., for the most part, hard and glossy leaves, as in Polygala 

 sibirica, L., and are often distinguished by the erect position of 

 the leaves. This is seen in a comparison of Viola Patrinii, DC. 

 with the shade-loving V. serpens, Wall., and Pimpinella Les- 

 chenaultii, DC. with P. Candolleana, W. & A., from which it is 

 otherwise hardly distinguishable except by the ripe fruits. Of 

 under shrubs, two species of Leucas have narrow hairy Leaves, 

 and are, in other respects also, very nearly alike. But one L 

 helianthemifolia . Deaf, is most abundant on the eastern side of 

 the Nilgiri platen u . near Kotagiri, and also on the Pulney downs 

 near Kodaikanal ; the other L. suffruticosa, Berth, takes its place 

 on the western side towards Pykara. This seems to be a 

 seasonal difference, for the western side is wettest m the sum- 

 mer from the S.-W. monsoon, the eastern side and the fulnexs 

 near Kodai get most of their rain later on in November The 

 eastern and western sides of the Nilgiri plateau are also distin- 

 guished bv the abundance of the two shrubs Dodonaea wosa, 

 Linn, and Rhodomvrtus tomentosa, W ivM, the Hill-gooseberry 

 on the former ; and of Hypericum mysorense, Heynt on the 



° the What appears to be the direct effect of the ^i™"™* £ 

 regard to the supply of water is illustrated in a species of Knoxy , 

 one of the Rubfaceae. This species, Knoxia mollis \ . , ■ A 

 is one of the commonest plants everywhere except m ru* 



shade or on bare rock. It oeeurs in *^^^^S 



the one in drv hill sides has a loose corymb of flowers standing 



