120 VEGETABLE ORGANOGRAPHY. 



Comus florida is so large, so coloured, and enjoys so 

 much the function of petals, that it has given this pretty 

 under-shrub its specific name; the bracts of Hortensia 

 are so coloured and so near the flower, that there are 

 few beginners who do not take them for true petals. 



If we are surprised at seeing bracts or sepals taking a 

 petaloid appearance, and if we wished to deduce from it 

 that these organs were not originally foliaceous, we should 

 be quickly undeceived, both by the great number of ana- 

 logous organs which present the appearance of leaves, 

 and by the examples of leaves which take petaloid 

 colours. Thus, several species, such as Atriplex hor- 

 tensis, are indifferently wholly green, or entirely red; 

 others, such as different species of Amaranthus, and 

 especially A. tricolor, take under different circumstances, 

 or in different places of the same plant, very decided 

 yellow or red tints ; others, such as Caladium bicolor, 

 have the centre of the leaf constantly marked with a 

 large rose-coloured spot, as brilliant as the petals. There 

 are some, such as Tradescantia discolor, Begonia discolor, 

 in which one of the surfaces of the leaf is of the most 

 beautiful red colour ; in other cases the leaves are 

 marked here and there with red spots in some species of 

 Caladium, with white ones in Begonia argyrostigma, 

 and with black ones in Arum vulgare. Let us also ob- 

 serve, that towards the end of their life the leaves of a 

 great number of trees take red or yellow tints, which are 

 usually connected with the colour which the fleshy fruits 

 of the same trees take when ripe. 



All these examples, which could be easily multiplied, 

 and where we see parts naturally green become coloured, 

 tend to prove that this difference is far from being as 

 essential as might be supposed. If chemists should 

 show that the resinous colouring matter, or the Chro- 

 mule, is not perceptibly different when green (and then 



