268 



ORGANOGRAPHY. 



ventral sutures directed towards the backs of the inner car- 

 pels ; or if there are several whorls, the component carpels of 



Fig. 591 



Fig. 591. Section of the flower of the Strawherry. The thalainus is nearly 

 hemispherical, and bears a number of separate carpels on its upper 

 portion. — Fig. 592. Section of the ripe pistil of the Raspberry, showing 

 the conical thalamus, I. Fig. 593. Pistil of Pheasant's Eye (^Adonis). 



each wliorl are arranged in like manner with regard to those 

 within them. When the thalamus is convex, or in any way 

 prolonged upwards, the innermost carpels are upon a higher 

 level than the outer; or when the thalamus is concave, the 

 outer carpels are uppermost. These different arrangements 

 modify very materially the appearance of the flower. The mu- 

 tual relations of the component carpels, and other matters con- 

 nected with their order of development, may be easily traced in 

 apocarpous pistils, but in those cases where carpels placed under 

 like circumstances become united and form syncarpous pistils, 

 they give rise to very complicated structures, which will be 

 alluded to hereafter. 



2. Syncmjwus Fistil. — Having now considered the simple car- 

 pel, and the compound apocarpous pistil, we pass to the con- 

 sideration of the compound syncarpous pistil, or that in which 

 the component, carpels are more or less united. We have already 

 seen in speaking of the floral envelopes and androecium, that the 

 different parts of which those whorls are respectively composed 

 may be also distinct from each other, or more or less united. 

 Prom the position of the carpels with respect to each other, and 

 from their nature, they are more frequently united than any other 

 parts of the flower. This union may take place either partially or 

 entirely, and it may commence at the summit, or at the base of the 

 carpels. Thus in the former case, as in many Asclepiadacese and 

 Xanthoxylon fraxineum (fig. 594), the carpels are united by their 

 stigmas only; in the Bictamnus fraxinella {fig. 610) the upper 

 parts of their styles are united ; while in the Labiatse (/^. 595, s) 

 and most Boraginaceae {fig. 596, d) the whole of the styles are 

 united. In all the above cases the ovaries are distinct. These 



