STOVE PLANTS IN THEIR NATIVE TROPICS. 51 



Hence in the tropics we find marvellous diversity of shapes and 

 adaptations, and from this comes the difficulty of understanding 

 that there is a unity which connects even the "most varied forms. 

 The structure of plants may be illustrated by the architecture of 

 buildings, in which the elementary factors are walls, floors, and 

 roofs, to which we might add chimneys and Avindows. These 

 are found in cathedrals and- wayside shrines, in palaces and cot- 

 tages ; however much they may be disguised by decoration or by 

 extrinsic additions of every kind, we can still recognize them and 

 comj)are them with each other ; A\'e can penetrate the most com- 

 plete disguise, and recognize them even when they have outlived 

 their usefulness and exist only as ornamental vestiges, like make- 

 believe chimneys or false windows. The recognition of these 

 simple elements of architecture is not always easy, but it is 

 always worth while, for we are thereby enabled to trace relations 

 between the most widely separated structures, and to gain some 

 insight into the order of their development. We can even see 

 how the wayside shrine grew into a cathedral, and w^e can trace 

 the steps by which the development has passed along its course. 

 The recognition of these elements is of further use in such study, 

 since it shows that form is, within certain limits, independent of 

 material, and that whatever material is used must be so disposed 

 that its burdens are kept within its strength. This illustration 

 may now be applied to plants and their underlying architecture. 



Tt is everywhere held truly by botanists that the different 

 organs of all flowering plants are referable to root, stem, and leaf. 

 Here we have the floor, the walls, and the roof. Perhaps root- 

 hairs deserve the same rank, but for the present purposes we 

 must restrict ourselves to the root, stem, and leaf, or even to the 

 more essential stem and leaf. 



This reduction of all parts of a flowering plant to such simple 

 elements was the discovery, or rather inspiration, of the poet 

 Goethe, who saw in a misshapen rose, with green leaves where 

 there should have been fragrant petals, the reading of one of the 

 riddles of nature. About the same time — the close of the last 

 century — Auguste de Candolle, a botanist of the highest rank, 

 was led by a careful comparison of the arrangement of leaves on 

 stems with the parts of the flowers, to the conclusion that the 

 flower is a shortened branch, with its parts arranged in an orderly 

 manner, and adapted to special uses. At first botanists were 



