AESTIVATION, OR PR^EFLORATION. 137 



times a clear case of binary instead of quaternary, t. e. to be 

 counted as two pairs of opposite leaves ; yet it may be a single 

 whorl of four, notwithstanding the imbrication. Or these four 

 leaves may even, in some cases, be regarded as a portion of a 

 depressed spiral, say of the f order with one piece omitted, and 

 the others adjusted so as to fill the space. 



257. There are various deviations from normally imbricative 

 aestivation, especially where the members are five, occurring 

 some in regular but more in irregular flowers, which need not be 

 referred to here. One, for which no specific name is requisite, 

 is a case merely of excessive overlapping in the regular way ; 

 namely, where each piece completely and concentrically encloses 

 the next interior, as shown in Fig. 259, representing three petals 

 of Magnolia Umbrella. This the French botanists have called 

 convolute aestivation, because the individual leaves are involute 

 in a manner approaching the convolute vernation of Linnaeus. 

 Another is the Vexillar, as in the Pea tribe (Fig. 306), where 

 members which should be external have somehow developed as 

 internal, both in calyx and corolla. A third (which has received 

 the usually quite meaningless name of Cochlear, spoon-like, 

 and is also that to which most French botanists singularly re- 

 strict the name of imbricative) is a state exactly intermediate 

 between the quincuncially imbricate and the convolute or 

 



contorted. In it, one leaf is wholly outside, one wholly inside, 

 and three with one margin inside and the other outside. It occurs 

 under two modifications, viz. with the innermost leaf remote from 

 the outmost (Fig. 261), and with it next to the outermost as in 

 Fig. 262. In view of the intermediate character, we had 

 applied to this the somewhat awkward name of Convolute-imbri- 

 cated To bring Fig. 261 back to the quincuncially imbricate 



1 It would not be amiss, therefore, to name one of these modes, viz. that 

 of Fig. 261, Subimbricate, and the other, Fig. 262, Subconvolute. George 



FIG. 261. Quincuncial imbricate modified toward convolute by one edge of the 

 second leaf developing inside instead of outside of the adjacent edge of the fourth. 



PIG. 262. Convolute modified toward imbricate by one leaf having a margin inside 

 instead of outside its neighbor. 



FIG. 263. Convolute, or convolutive, or contorted (twisted) aestivation, in diagram. 

 In these throe diagrams, the dark circle above represents the position of the axis, tho 

 flowers being axillary. 



