VARIETIES OF CIRCULAR ASTIVATION. 219 
ponent parts of the calyx and corolla, because the stamens and 
carpels, from their peculiar forms, can give us no such arrange- 
ments of their parts as are exhibited by the more or less 
flattened floral envelopes. 
In describing the modifications of zestivation, we have, as in 
the case of vernation, to include : Ist, the disposition of each of 
the component parts of the floral envelopes, considered inde- 
pendently of the others; and 2nd, the relation of the several 
members of either of the floral envelopes taken as a whole in 
respect to one another. With regard to the disposition of each 
of the component parts of the floral envelopes considered inde- 
pendently of the others, the same terms are used as in similar 
modifications of vernation (page 156), with the addition of the 
crumpled or corrugated form, which is not found in the parts of 
the leaf-bud. This latter variety may be seen in the petals of the 
Poppy (Papaver), and Rock Rose (Helianthemim) ; and it derives 
its name from the parts being irregularly contracted into wrinkled 
folds. 
With respect to the relation of the several members of either 
of the floral envelopes taken as a whole to one another, various 
Fig. 445. Fic. 446, Fic. 447. Fic. 448. 
Aa Neo 
Fig. 445, Diagram to illustrate valvate estivation.— Fig. 446, Diagram to 
illustrate induplicate zstivation.— Fig. 447. Diagram to illustrate redu- 
plicate zestivation.— /%g. 448, Diagram to illustrate contorted or twisted 
zstivation. 
modifications occur, all of which may be arranged in two divisions: 
namely, the Circular, and the Imbricated or Spiral Aistivation. 
The former includes all those varieties in which the component 
parts of the whorl are placed in a circle, and in nearly the same 
plane : and the latter those where they are placed at slightly 
different levels in a more or less spiral manner, and overlap one 
another. 
1. Varieties of Circular Aistivation.—We distinguish three 
well-marked varieties of circular zestivation, i.e. the valrate, in- 
duplicate, and reduplicate. The valvate (fig. 445) may be seen in 
the calyx of the Lime, and in that of Guazuma wlmifolia ; inthis 
variety the component parts are flat or nearly so, and in contact 
by their margins throughout their whole length without any 
overlapping. This variety of zestivation may be generally dis- 
tinguished, even when the flowers are expanded, by the margins 
