66 



ROYAL HORTICULTURAL SOCIETY. 



According to the degree of shelter which the valleys of these 

 ridges afford, according to diversity in the elevation and aspect, 

 according to the presence of some of the original Eucalyptus and 

 Acacia trees in some portions of the ground, and according to 

 the shelter afforded by the upgrown vegetation of tall shrubs in 

 other portions of the garden, the effects of the frost must have 

 been necessarily modified, especially in so extensive an area. 



The particular atmospheric current at the time of a frost has 

 also an important influence on the vegetation. Hence in some 

 positions plants became slightly, in some severely injured ; and, 

 again, a plant which in a somewhat sheltered spot was manifestly 

 touched by the cold, would remain uninjured in another perhaps 

 not distant but more favourable locality. All the perennial her- 

 baceous plants which are here recorded as severely injured, sprung 

 from the root again, while the shrubs or arborescent species 

 were uninjured by the transient frost in their stem or main 

 branches. Small plants of such may, however, entirely succumb. 

 A rough bower, crudely constructed of boughs, affords to the more 

 tender plants a temperature approximately 4° higher than that 

 of the open ground. Hence Cinchonse, Coffee, and many other 

 prominently utilitarian plants intended for the warm fern- tree 

 gullies of our ranges, would scarcely be affected under such 

 cover, while the same species exposed to the full inclemency of 

 the weather, and particularly if subjected simultaneously to a cur- 

 rent of wind, would be extremely injured. 



It may not be without interest to extend these observations, 

 especially as they may be utilized as indications of hardiness of 

 plants in South Europe and other countries of similar climate ; 

 and it may not be fruitless to give hereafter, also, a record of the 

 effect of the hot sirocco-like winds on the vegetation annually 

 so tryingly experienced. So also may it be of interest to pro- 

 mulgate the records kept in this garden with reference to the 

 times when plants from all the colder, temperate, and subtropical 

 zones are bursting into bloom. 



List of some plants in the Melbourne Botanic Gardens which were 

 not affected by frost. 



Lowest temperature, July 12, 1868, 27°-4 Fahr. in the air, 

 24° Fahr. on the grass. 



Aberia Caffra. Adenocarpus Cebennensis. 



Achras Australis. Adriana acerifolia. 



