E ENS ae oe 
IMBRICATIVE XZSTIVATION. 709 
count this variety has been termed vewillary imbrication. This 
variety of imbrication, however, occurs frequently im the flowers 
of many plants along with the regular imbrication, as shown in 
the examples of Rubus odoratus and Pyrola elliptica (Tables I 
and IT). When the internal part is adjacent to the external part 
ee 
Nae 
(Figs. 121, 122), the spiral makes but a single turn to form the 
whorl. The direction of the spiral is shown by 5 lying on the 
right or on the left of 1. This second variety is perhaps to be 
met with only as a casual variation from the other modes. I know 
of no flowers in which it is the only mode of æstivation, but the 
extent to which it occurs in many flowers is shown by the example 
of Rubus odoratus (Table I). 
Fig. 123. Fig. 124. 
4 a 
5 5 : 
2 
2 
I i 
; 9. The second variety of irregular imbrication passes easily 
into contortive æstivation by 5 throwing out one edge over 
This also is shown by some of the flowers of Rubus odoratus 
Passing into the contorted mode 
10. The imbrication of the flower sometimes shows a fixed re- 
lation to the axis, and whether there be such a relation or not, 
needs to be carefully observed. When the inflorescence is definite 
the flower terminates the axis and of course there is no other re- 
lation. Hence the position of the external and internal parts is 
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