of the Flower of ike VaytilioimcesQ. 155 



The cause of the cohesion is correctly explained by the reci- 

 procal pressure in the flower bud, without however contri- 

 buting in any way to the explanation of the very remarkable 

 irregularity of the flowers. 



The cohering-leaved calyx, however, as well as the position 

 of the ovarium with respect to the other floral parts, appear 

 to furnish the best explanation of this irregularity. 



From the double circle of anthers present in all decandrous 

 Leguminos(B, and actually to be observed in the embryonal 

 state of the floral bud, we obtain an explanation of the alter- 

 nation of the petals and ovaries which we find realized in Af- 

 fonsea, and indicated in the other one-podded LeguminoscB by 

 the position of the ovarium between the two carinal petals. 

 This ovarium is during the flowering period in general sessile, 

 or merely provided with so short a petiole that it does not 

 project out of the tubular calyx. Consequently an action on 

 the other floral parts cannot be denied to this ovarium, as it 

 frequently attains to a considerable size, and this action is 

 manifested by pressure on the adjacent organs, which on that 

 account are greatly inclined to cohesions in their still paren- 

 chymatous consistency. Since the petals in proportion to the 

 length of the calycinal tube can generally only be designated 

 as shortly unguiculated, nay in several genera a great portion of 

 the lamina is even still situated in the calyx, the lateral petals 

 standing nearest to the ovarium cohere at their inferior mar- 

 gins very frequently, where the pressure which the calyx and 

 ovarium jointly exert is most powerful, and form the carina. 

 This pressure is even so considerable in the genus Jonesia, 

 Rxb., that the petals are from the first entirely suppressed, 

 and further the ovarium coheres at its inferior suture through 

 its entire length with the perianthium, as I have observed in 

 several undescribed species of this highly instructive genus. 

 In the Cdesalpiniece there are several genera with only from 1 

 to 3 petals, these then constantly stand in the place of the 

 vexillum and of the wings {al(B). — Perhaps the absence of the 

 other petals may be deduced from hence ? Direct observation 

 can only decide this question. Yet we observe in TamarindiLS 

 Indica, L., at the place where the two absent petals should 



M 2 



