INTRODUCTION. 29 
acters on which more constant reliance can be placed; but these are 
not among the most obvious, such as the inexperienced Botanist would 
first attend to. For example, the number of stamens is a character 
to which little importance can be attached; since this is liable to 
vary extremely among the genera of ae every order,—in many 
cases among the species of the same genus,—not unfrequently also 
among individuals of the same species,—and even in different flowers 
on the same plant. Yet there are particular orders, in which the num- 
ber of stamens is very constant throughout, and is very characteristic of 
them. The most important characters afforded by the stamens are drawn 
from their mode of origin from the lower part of the flower. They may 
arise, like the sepals and petals, from the disk, beneath the ovary; in 
this case they are said to be hypogynous (designating their origin from 
beneath the female part of the flower.) But it may happen that the 
sepals and stamens arise together, (these parts being opposite in a 
regular flower, whilst the petals alternate with them so as not to prevent 
their adhesion,) and that they adhere for a part of their length, so that 
the stamens appear to arise from the calyx, and come away with it when 
it is detached; in this case or when they adhere in a similar manner to 
the petals, they are said to be perigynous, having their origin arownd 
the female organ. Lastly, when the calyx embraces the ovarium, it also 
closely envelopes the stamens which are not freed from it except at the 
top of the seed-vessel ; in this case, the stamens, appearing to arise from 
the top of the ovarium are said to be epigynous, being seated upon the 
female organ. Peculiarities in the mode in which the anthers open to 
disperse the pollen are sometimes characteristic of particular orders ; 
thus the Berberry and Laurel tribes have anthers bursting by valves; 
and the Heaths have anthers opening by pores. But such peculiarities 
are found in other genera, amongst orders which do not possess them, 
and ora must not therefore be implicitly relied on. 
34. Of all natural characters, those furnished by the structure of the 
central parts of the flower are perhaps subject to the fewest exceptions; 
yet these are not such as are the most evident to the ordinary observer. 
On the number of styles, as already stated, little reliance can be placed 
for the establishment of important distinctions, but as it is less liable to 
vary than is that of the stamens, it may often be useful in the separation 
of genera. A much more decisive character is afforded by the degree 
of adhesion among the carpels; when they remain distinct from each 
other, the ovary is said to be apocarpous (carpels apart ;) and when they 
are compactly united, it is termed syncarpous (carpels together.) There 
are few Natural orders in which one or other of these conditions does 
not prevail, to the entire exclusion of the other; so that plants which ° 
(Oe Sens revemblance in imagen for but differ in this, mt 
