708 IMBRICATIVE STIVATION. 
the same flowers ; this is the arrangement of the four sepals of the 
White Water Lily (Nymphcea odorata). 
8. A pentamerous imbricate whorl, also, presents two cases. 
I. Two parts of the floral whorl are external, two parts are in- ; 
ternal and one is intermediate (Figs. 117, 118). This is regular 
pentamerous imbrication. It corresponds to the quincuncial or 2 k 
arrangement of leaves. The spiral makes two turns to form the 
whorl. The successive members of the cycle may be numbered 
1, 2, 3,4 and 5 (Figs. 117, 118). 1 and 2 are the external parts; 
4 and 5 are the internal parts; and 3 is the intermediate part. 1 
has 3 and 4 adjacent and 2 and 5 opposite. One edge of 3 is cov- _ 
ered by the adjacent edge of 1, while the other edge of 3 overlaps 
the adjacent edge of 5. The succession of the numbers of the 
cycle in the whorl, in one direction, is 1, 4, 2, 5, 3; in the other 
direction, 1, 3, 5, 2,4. 8 shows the direction of the spiral ; when — 
it lies on the right of 1, the spiral winds from left to right, amt 
the parts of the whorl are imbricate + (Fig. 117) ; when it lies on 
the left of 1, the spiral winds from right to left, and the parts are 
imbricate — (Fig. 118). 
II. One part of the floral whorl is external, one part is internal 
and three parts are intermediate. This is irregular pentamerous 
imbrication. There are two varieties of this case, according % 
the internal part is opposite or adjacent to the external part. 
BORE Tecan SPS Se ae ame ae eee 
Spee 2 ies ro eee eee 
_ 
a 
Rte eae 
Set 
penis So bibles 
Fig. 119. Fig. 120. 
+ —_ 
_ throws out one edge over the adjacent edge of 2; 50 
and 4 have one edge out and one edge in, the same 48 5: eo 
between 1 and 5 still shows the direction of the spiral. sass 
the æstivation of papilionaceous flowers. In these the large petal 
called the vexillum or banner overlaps the others, and on er : 
