GIWGRAPHICAL BOTANY. 351 



are partly limited to lists of the localities of the autumnal 

 plants which he was then able to collect. The alpine 

 flora, even at elevations of 7 SO 00' was but slightly 

 represented by its characteristic forms (ii, p. 69) ; these 

 high mountains are altogether more sterile than the Alps, 

 which the author attributes primarily to the rarity of 

 glaciers in the Caucasus, as if the alpine meadows of the 

 Ty r l were only fertilized by melting ice. He then goes 

 so far as to assert (p. 91), that the disintegrated soil of 

 Ossetia, the steep rocks and precipitous defiles of this 

 alpine district, are not adapted to the production of 

 humus, and that this is the cause of the total absence of a 

 luxuriant vegetation there. But the author is not clear 

 upon this point, and does not separate general from local 

 conditions ; for he speaks at the same time of clay-slate 

 plateaux, but little supplied with water and destitute of 

 woods, extending between the defiles and valleys to the 

 ridge and lateral offsets of the Caucasus. Upon this form 

 of mountain and peculiarity of soil the alpine poverty of 

 Ossetia appears to depend ; that it also prevails over the 

 well- wooded slopes of the northern Caucasus is not pro- 

 bable. But Ossetia shares this deficiency of alpine 

 vegetable forms with the mountains of the south of 

 Europe, where alpine pastures abounding in species are 

 but rarely developed, and where this phenomenon is occa- 

 sioned by the deficiency of water upon narrow crests and 

 summits. Ossetia does not possess the fine forests of 

 the northern promontories of the Caucasus. Even in 

 the true forest region there is a perceptible deficiency of 

 wood, and frequently the soil is scarcely covered with a 

 scanty underwood : e. g. at Zrchinwall (p. 55) consisting 

 of Corylus, Cornus mascula, Paliurus, Crattegus, Prunus 

 insititia, and Jumperus. The traveller only met with 

 wooded slopes at Dschedschora, in the district of Gudaro, 

 (p. 82) ; here deciduous trees predominated, and the 

 Coniferae present were Pinus abies, picea, and orientalis, 

 Taxus, and Juniperus communis. The deciduous forests 

 consisted of the oak, beech, rnaple, lime, and alder (Quercus 



