680 ZONES AND REGIONS [Pt. Ill, Sect. Ill 



tetragona, Empetrum), or under a shaggy coating of hairs on the lower 

 surface of the leaf (Ledum, Dryas octopetala, Potentilla nivea, P. multi- 

 fida, Loiseleuria procumbens, Phyllodoce). In other cases, the stomati- 

 ferous under-surface of the leathery leaf is covered only by a thick coating 

 of wax, which certainly reduces transpiration (Andromeda polifolia, Vac- 

 cinium Vitis-Idaea, Salix glauca, S. reticulata). Among grass-like plants 

 a whole list of extreme northern species might be named, which, owing 

 to the rolling up and the dryness and the strong cuticularization of their 

 leaves, must be included in the type of steppe-grasses ; such are Hiero- 

 chloa alpina, Festuca ovina, Nardus, Carex rupestris, and C. pedata. On 

 the other hand, protection by a dense felt of hairs is weakly represented in 

 extreme northern lands (Antennaria, Draba, Eritrichium, Salix Lapponum, 

 S. lanata).' 



The frequent tendency in plants of windy stations to form hemispherical 

 cushions by rich and dense ramifications, is exhibited by various arctic 

 species, including Draba alpina, Papaver nudicaule, Eritrichium villosum, 

 Cerastium alpinum, Aira caespitosa. According to Kjellman, this feature is 

 specially marked at the most unfavourable stations (Fig. 405). He says 1 : — ■ 



' Of the 23 species that inhabit the northernmost point of Asia, no less than 

 13, owing to copious branching, have the shape of dense spherical or hemispherical 

 masses. These species are : — Eritrichium villosum, Saxifraga oppositifolia, 

 S. decipiens, Cardamine bellidifolia, Draba alpina, Papaver nudicaule, Stellaria 

 longipes, Cerastium alpinum, Alsine macrocarpa, Oxyria digyna, Catabrosa algida, 

 Aira caespitosa, and Luzula arcuata, all of which in other places appear in forms that 

 are feebly branched and but little inclined to bushiness.' 



v. REPRODUCTIVE ORGANS. 



The arctic climate, so unfavourable to the vegetative functions, possesses 

 no factor decidedly hostile to the production of flowers, and its physiological 

 dryness is even favourable to this. As a matter of fact, arctic plants are 

 generally distinguished by marvellous wealth of flowers, which strike the 

 eye owing to the contrast of the weak development of the foliaged shoots, 

 and have therefore been recorded by most polar travellers. The wealth of 

 flowers is obviously greatest in places that are most unfavourable to vege- 

 tative organs. At such spots, exposed to every inclemency of the weather, 

 Kjellman frequently saw the cushions of Papaver nudicaule with about a 

 hundred open flowers, carpets of Eritrichium villosum quite blue, spheres of 

 Draba wholly bright yellow or wholly white 2 . 



To the growth of the individual parts of a flower the arctic climate is 

 also less unfavourable than it is to the growth of vegetative shoots, because, 

 as has been previously explained; temperatures beneficial to the develop- 



1 Kjellman, op. cit., p. 496. 2 Id., p. 497. 



