113, 114.] 



METAMORPHOSIS OF THE FLOWER. 



133 



naturally results from the spiral arrangements so com- 

 mon in phyllotaxy, while the valvate and contorted 

 seem identified with the opposite or whorled arrange- 

 ment. The principal varieties are the following : The 

 Quincuncial, consisting of five leaves, two of which 

 are wholly without, two wholly within, and one partly 

 both, or one margin out, the other in, as in the Rose 

 family (422). This accompanies the two fifths cycle in 

 phyllotaxy, and corresponds precisely with it, each 

 quincunx being in fact a cycle with its internodes 



t) 



427 



426 



Diagrams of flowers (as seen by cross-sections). 426, Jeffersonia diphylla o, ovary ; s, stamens ; d, inner 

 row of petals, aestivation triquetrous ; b, outer row of petals, aestivation contorted; c, sepals, aestivation 

 quincuncial. 427, Lily. 428, Strawberry. 429, Mustard. The pupil will designate modes of aestivation. 



suppressed. (Fig. 300, 266.) The Triquetrous, con- 

 sisting of three leaves in each set, one of which is out- 

 side, one inside, and the third partly both, as in Tulip, 

 Erythronium, agreeing with the two thirds, or Alder 

 Cycle ( 265). The Convolute, when each leaf wholly 

 involves all that are within it, as do the petals of Mag- 

 nolia ; and lastly, the Vexillary, when one piece larger 

 than the rest is folded over them, as in Pea (425). 



340. Plicate or folded aestivation occurs in tubular 

 or monopetalous flowers, and has many varieties, of 

 which the most remarkable is the supervolute, where 

 the projecting folds all turn obliquely in the same 

 direction, as in the Morning-glory, Thorn-apple. 



Different modes of aestivation may occur in the 

 different whorls of the same flower. 



