231 
RUDIMENTS OF THE NATURAL SYSTEM OF BOTANY, 
NO. V. 
Continuing our brief analysis of the various parts of a plant which furnish 
marked characters for the definition of Natural Orders, we next reach the second 
and most showy feature in the inflorescence, which is termed the corolla. A 
corolla is usually composed of coloured leaves or petals, situated within the calyx, 
and generally distinguished therefrom by its greater size and the superior richness 
of its hues, but most accurately known by its position, the calyx being always on 
the outside. Thus, in Lilies, and the flowers of many other bulbous plants, the 
whole blossom is called the perianth, while the outer segments or sepals, though 
similar to the rest, are properly the calyx, and the inner ones, or petals, form the 
corolla. 
In some plants, the corolla is ever present, unless removed by casualties or 
disease ; and these take the name of dichlamydeous. Two divisions are observable 
in this group, which are very readily known by their external aspect, deriving their 
title from possessing one or more petals. Monopetalje, for instance, consist of 
flowers which often have manifest segments, but have no actual separation all 
round the corolla, which is commonly of a bell shape. Polypetal^:, on the other 
hand, have their corolla partitioned completely down to its base. Those plants 
which have no true petals are denominated Apetalce. 
The aestivation, or bud-state of a corolla, is occasionally but rarely useful in 
fixing the position in the Natural System of the plant bearing it. It is either 
valvate or contorted ; the former being a condition in which it projects itself 
straightly and opens regularly, and the latter having a twisted appearance, which 
unrolls itself gradually with the progress of expansion. 
From the contour of the corolla, important characters are frequently deduced, 
which, on account of their simplicity, tend much to assist the student. A corolla 
is said to be regular when all its divisions present a near equality in size and shape, 
and irregular if they vary considerably. Of both these forms, there are many 
varieties, which serve to detach several orders. 
Proceeding still nearer to the centre of the flower, we discover a greater or less 
number of small processes, which comprise the sexual organs of plants. They are 
usually regarded as metamorphosed leaves — an hypothesis which cannot be admitted 
until the outer members of animals are reduced to modifications of one type. It 
is here, indeed, that the tendency of scientific writers to indulge in visionary 
theorizing is most painfully conspicuous. Assign to plants no specific propagational 
organs, and their reproduction becomes entirely fortuitous, the beautiful harmony 
of Nature is destroyed, and a link in the scale of creation is broken. 
As vegetable metamorphoses, or the change of all the minuter parts of plants 
from the common structure of leaves to that which they usually assume, is a point 
