192 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY 



mountain masses of south-eastern Switzerland, including the Lepontine 

 Alps in the west and the Rhaetian Alps in the east. His chief object 

 is to present " a picture of plant life at its extreme limit," and though 

 nearly half of his work, which has also been published in book form,* 

 is occupied by lists of species with their habitats, he has throughout 

 dealt with their nival zone from an ecological rather than a fioristic 

 standpoint. The climatic snow-line, forming the lower limit of the 

 nival zone, lies at about 2650 metres in the western (Sardona and 

 Gotthard) region and at about 2960 m. in the eastern (Bernina) region, 

 and the flora of the nival zone in the area investigated includes 224 

 vascular plants. The author divides the plant associations into three 

 main sub-zones — (i) a lower, up to 150 m. above the snow-line, 

 dominated by grasses ; (2) a middle, up to 550 m. above snow-line, 

 characterized by Dicotyledons ; and {3) a summit flora devoid of 

 flowering plants and consisting only of Thallophyta (Algae, Fungi, 

 Lichens) which extend up to the highest peaks. Wind is one of the 

 most important factors in the environment of the nival flora, and the 

 author devotes an interesting chapter to the effects on the nival vegeta- 

 tion of the strong winds that prevail in the high Alps, especially in 

 winter. The drying action of these winds excludes all except a few 

 hardy species [Saxifraga retusa, S. caesia, Androsace helvetica, Gentiana 

 hrachyphylla, &c.) from the snow-free but exposed places. The low- 

 growing tufted, patch-forming, and cushion plants are furrowed, 

 undermined, and distorted by the mechanical action of the wind 

 and the fine snow which it sweeps over the plants as a snow-blast " 

 comparable with the fierce sand-blast in deserts. 



Other interesting sections are that dealing with the ripening, 

 viabihty, and dispersal of the seeds of nival plants. The author finds 

 that the conditions above snow-line are not so unfavourable for the 

 ripening of seed as has usually been supposed, for in 25 species collected 

 above 3100 m. the seeds were fully ripe and capable of germination, 

 and he believes that the nival flora does not depend to any great extent 

 upon the carriage of seeds from lower levels for its maintenance. Many 

 of his observations are of considerable practical interest to those 

 concerned with the collection and cultivation of alpine plants, though 

 of course the great majority of the nival species also occur at lower 

 elevations. In more than 20 per cent, of the nival species the fruits 

 with their seeds remain on the plant over the winter, and in some 

 cases for two or three winters, and the seeds in such cases show a higher 

 germination capacity than seeds collected in the autumn after flowering. 

 Shrubs like Empeirum, Vaccinium, and Juniperus occur here and there 

 in the nival zone, arising from seeds carried by birds, but they are 

 usually dwarfed plants and are always sterile. From various facts 

 and considerations which he brings forward, the author concludes 

 that in the Glacial Period a relative^ rich flora, similar to the nival 

 flora of the present day, persisted in the interior of the Alps ; for 



* Vegetationsverhdltnisse der Schneestuje in den Rdtisch-Lepontischen Alpen, 

 Georg & Co., Bale, price 20 marks. 



