THE ANGIOSPERMAE 



1I2I 



carpels are traceable and may be disposed of in one of four ways: (i) they 

 may disappear below the carpel level ; (2) persist in the axis either separately 

 or anastomosed ; (3) fuse with the carpel trace ; (4) enter the carpel as 

 supernumerary traces (as above). 



The variant conditions of cohesion and adhesion naturally affect the 

 floral anatomy. In the cohesion of 3-trace organs, either sepals or carpels, 

 the marginal bundles, which in the case of carpels are the ventral traces, 

 tend to become concrescent, even down to the base. Conversely they may 

 be concrescent at the base and free above. In a coherent calyx, e.g., in the 

 Labiatae, the varying degrees of concrescence of the traces affect the number 

 of " nerves " or ridges displayed, which may be a generic character (Fig. 

 1097). The condition of adhesion is well shown in epipetalous stamens, 



h/hhM^, 



Fig. 1097. — Diagrams showing the vascular similarity under cohesion, in 

 ovarv, corolla and calvx. In each case there is cohesion of the lateral 

 bundles. Top, ovarv of Reseda odorata. Middle, corolla of Heli- 

 imthtisdivaricatus. Bottom, calyx oi Agrostemma githago. {After Eames.) 



