340 A. Gray— #stivation and its Terminology. 
‘s With some pieces of the set wholly exterior in the bud to 
others. 
II. With each piece covered at one margin, and covering by 
the other. 
III. With each piece squarely abutting against its neighbors 
on either side, without overlapping. 
In modes II and III, the pieces are all on the same level and 
are to be viewed as members of a whorl. In mode I, although 
they may sometimes be members of a whorl, some parts of 
which have become external to others in the course of growth, 
they may, and in many cases must belong either to two or more 
successive whorls (as in the corolla of Papaveracee, and even the 
calyx of Crucifere, the upper or inner of course covered by the 
lower or outer), or to the spiral phyllotaxy of alternate leaves. 
The type of the latter, and the common disposition when the 
parts are five, is with two pieces exterior, the third exterior by 
one edge and interior by the other, and two wholly interior. 
This is simply a cycle in 2 phyllotaxy, the third piece being 
necessarily within and covered at one margin by the first, while 
it is exterior to and with its other margin covers the fifth, this 
and the fourth being of course wholly interior. So, likewise, 
when the parts are three, one exterior, one half exterior, and 
one interior or overlapped, the zestivation accords with 4 phyllo- 
taxy. When of eight or higher numbers the spiral order 1s 
usually all the more manifest. hen of four or six, the case 
is one of whorls (opposite leaves representing the simplest 
whorl), either of a pair of whorls (as in Epimedium, Berberis, 
&e.), or a single whorl, the parts of which have overlapped 10 
cyclic order. : 
2. As to the terminology. lLinneus in the Philosophia 
Botanica treats only of Vernation, there termed Foliatio. For 
this the former term was substituted, and that of estivation 
for the disposition of ~~ in a flower-bud, introduced, as I 
781. e 
defined only by reference to the section vernatio, and valvaia, 
unhappily explained by a reference to the glumes of Grasses, 
also “inequivalvis; si magnitudine discrepant.” IJmbricata 1s 
the only term besides valvata which directly relates to the 
arrangement of petals, &c., inter se; and the reference takes US 
back to something “ tectus, ut nudus non appareat,” covered as 
with tiles we may infer. In the Philosophia Botanica, under the 
lele, superficie recta, sibi invicem incumbunt.” This would 
apply either to mode I, or mode II, according as invicem 18 
