198 PHYSIOGNOMY OF PLANTS. 



The Escallonia floribunda offers in its geographical distribu- 

 tion one of the most striking examples, in the habitat of 

 the plant, of proportion between distance from the equator 

 and vertical elevation above the level of the sea. In making 

 this statement I again support myself on the authority of 

 my acute and judicious friend Auguste de St.-Hilaire 

 (Morphologie vegetale, 1840, p. 52) : " Messieurs de 

 Humboldt et Bonpland ont decouvert dans leur expedition 

 PEscallonia floribunda a 1400 toises par les 4 de latitude 

 australe. Je 1'ai retrouve par les 21 au Bresil dans un 

 pays elev6, mais pourtant infiniment plus bas que les Andes 

 du Perou : il est commun entre les 24.50' et les 25.55' 

 dans les Campos Gerses, enfin je le revois an Rio de la Plata 

 vers les 35, au niveau meme rocean." 



Trees belonging the group of Myrtacese, to which 

 Melaleuca, Metrosideros, and Eucalyptus belong, in the 

 sub-division of Leptospermea3, produce, by the peculiar dis- 

 position or direction of the leaves relatively to the undilated 

 leaf-stalk, (as do Acacias in which the leaves are replaced 

 by phyllodia, leaf-like petioles,) a distribution of stripes 

 of light and shade unknown in our forests of broad-leaved 

 trees. The first botanical travellers who visited New Hol- 

 land were struck with the singularity of the effect thus 

 produced, Eobert Brown was the first to show that this 

 strange appearance arose from the leaf-stalks (the phyllodia 

 of the Acacia longifolia and A. suaveolens) being expanded 

 in a vertical direction, and from the circumstance that the 

 light instead of falling on horizontal surfaces, falls on and 

 passes between vertical ones. (Adrien de Jussieu, Cours de 



