PHYSIOGNOMY OF PLANTS. 23 



Tamarindus are important members, is entirely wanting in 

 our temperate zone in the old continent, though found in 

 the United States, where, in corresponding latitudes, vege- 

 tation is more varied and more vigorous than in Europe. 

 The umbrella-like arrangement of the branches, resembling 

 that seen in the stone pine of Italy, is very frequent among 

 the Mimosas. The deep blue of the tropic sky seen 

 through their finely divided foliage has an extremely 

 picturesque effect. 



The Heath form ( 19 ) belongs more especially to the old 

 world, and particularly to the African continent and islands : 

 taking for our guides physiognomic character and general 

 aspect, we may class under it the Epacridese and Diosmese, 

 many Proteaceee, and those Australian Acacias which have 

 mere leaf-stalks instead of leaves (phyllodias) . This form 

 has some points of similarity with that of needle trees, and 

 the partial resemblance enhances the effect of the pleasing 

 contrast which, when these two are placed together, is 

 afforded by the abundant bell-shaped blossoms of the heaths. 

 Arborescent heaths, like some other African plants, extend 

 to the northern shores of the Mediterranean : they adorn 

 Italy, and the cistus-covered grounds of the south of Spain. 

 The declivity of the Peak of Teneriffe is the locality where 

 I have seen them growing with the greatest luxuriance. In 

 the countries adjoining the Baltic, and farther to the 

 north, the aspect of this form of plants is unwelcome, as an- 

 nouncing sterility. Our heaths, Erica (Calluna) vulgaris, 

 Erica tetralix, E. carnea, and E. cinerea, are social plants, 

 and for centuries agricultural nations have combated their 



