BOTANIC GARDENS. 319 



ecological and aesthetic requirements. A small portion is devoted 

 to aquatic plants, a second to an arboretum, another to an experi- 

 mental plot inclosed and accessible only to workers. In the entire 

 garden the instinctive ability of the naturalist is shown in the 

 selection of natural conditions for the specimens of the various 

 flora represented, and the alpinum may be regarded as a triumph 

 in the art of artificial culture. 



The alpinum is laid out in the northwestern part of the garden 

 on a rectangular plot of ground one hundred and ninety feet in 

 length and nine feet in width, near a stone wall seven feet high 

 and parallel to its length. On this plot are piled the rocks and 

 soil necessary for the culture of plants, in an uneven ridge, which 

 in one place is six feet in height. The materials used were princi- 

 pally the native stalactite limestone and gravelly soil and granite 

 from the Black Forest, forty miles distant. The limestone is 

 peculiarly suitable for the lower Alpine plants and lithophytes, 

 furnishing, as it does, innumerable cavities for the reception of 

 soil and secure foothold for plants which cling directly to the 

 rock. It has been found that the species from the higher Euro- 

 pean Alps refused to grow on such rock, and hence the granite 

 was procured for the section devoted to this group. The entire 

 structure is in many respects an admirable imitation of an east-to- 

 west mountain ridge. The northern side affords many shaded 

 crevices, and more or less shade to the whole is given by a num- 

 ber of small trees near by. 



The most difficult problems which have confronted the gar- 

 dener in the construction and management of the alpinum have 

 been those connected with the water supply. The water content 

 of such rocky soils is of course extremely small and needs almost 

 constant replenishment. In Nature this is done by water from 

 the melting snows above. Here it has been accomplished by a 

 system of branching pipes with many openings below and above 

 the surface, and a flow is allowed during the greater part of the 

 day. The drainage is carried away by cement conduits, and in 

 one place forms an Alpine lake eight feet in length and five feet 

 in width, which furnishes in its waters and on the overhanging 

 cliffs admirable conditions for a very rich flora. Near the lake 

 are growing several specimens of Edelweiss, which here becomes 

 somewhat longer stemmed than on its native cliffs, or in the 

 Alpine gardens where it is cultivated to satisfy the thirst of the 

 tourist for mementoes of " hazardous " ascents. 



Many of the Alpine plants are quite intolerant of lime salts 

 and grow best on the granite rocks, but the water supply used 

 here is taken directly from the city system and is very richly 

 charged with these substances, and as a consequence the cul- 

 ture of some of the plants of the higher slopes is impos- 



