84 THE FLOWERING PLANT. 
Two sepals are occasionally found, as in the poppy, and this may 
be here explained as a reduction from a higher number, probably 
once possessed. In a good many flowers the perianth consists of 
one whorl only, which is then considered to be, in most cases, a 
calyx. In cases of doubt it is best simply to use the general 
word pverianth. Here again we see reduction. It is also to be 
noted that in many small epigynous flowers (composites, umbelli- 
fers, &c.) occurring in dense clusters, the calyx is very much 
reduced in size, or even absent. Reduction may, lastly, be 
carried to such an extent that both corolla and calyx are absent, 
as in certain small inconspicuous flowers, like those of willow. In 
the great majority of gymnosperms (fir, yew, juniper, &c.) no 
perianth is present, but this does not appear to be a case of reduc- 
tion from a former condition. 
Mention has still to be made of arrangement in the bud, 
which, in the case of flowers, is called cestivation or prejflora- 
tion,! and corresponds to the prefoliation of foliage leaves 
- 49). 
a Cohesion.—The sepals are often quite free from one another, 
as in rose, buttercup, and wallflower, when the calyx is poly- 
sepalous or aposepalous. This is strikingly seen in poppies, 
where the sepals are caducous, 7.e., fall off very early. In many 
flowers, on the contrary, the sepals are more or less united into 
a tube. <A gamosepalous or synsepalous calyx of this kind occurs, 
for instance, in the bean, primrose, and Canterbury bell. We 
are here reminded of the cup-like or tubular structures formed 
by connate leaves and sheathing stipules. 
Adhesion.—According to the most modern views, the members 
of other floral whorls adhere but seldom to the calyx. It may 
not be amiss, however, to explain here some older ideas which 
caused the invention of certain terms that are still current in 
many books. The perigynous and epigynous conditions of the 
flower have been explained (p. 81) as the result of the growth 
of the floral receptacle into a cup-like structure, upon the rim of 
which sepals, petals, and stamens are inserted (fig. 37). This 
cup was formerly held to be part of a gamosepalous calyx, and 
was therefore termed the calyx tube, the real sepals being looked 
1 The ways in which individual leaves are arranged have been defined in 
the footnote to p. 49. Sepals and petals (as also foliage leaves) are disposed 
in the bud with reference to one another as follows :—I. open, the parts 
separated ; II. closed, the parts approximated: (1) valvate, touching at the 
margins ; (2) overlapping at the margin; (a) imbricate, both margins of one 
or more leaves covered ; (6) obvolute, every leaf with one covered and one 
uncovered margin. 
These points may be determined by cutting through the bud trans- 
versely 
