luiliinil l\imili) of Plants culled Coniposifu: 83 



to Coiupositae. It exists also in Ernodea, in which the lateral nerves, 

 though they give out externally a few branches, observe the same 

 course, and terminate in the same manner in the lacinite as those 

 of Compositoc. A similar disposition is observable in certain 

 genera of Solanacea?, as Datura and Cestrum, though in these the 

 lateral nerves arc more ramified, and their trunks generally less 

 distinct in the laciniae. It appears therefore that, in adopting 

 M. Cassini's theoretical expression for the vascular structure of 



point of adhesion, and in such a degree that the corresponding branches of the neighbour- 

 ing segments unite with each other considerably above the middle of the tube, forming a 

 common trunk, which is continued to the base of the ovarium; the five trunks thus formed 

 uniting internally with those from which the filaments originate, and externally with the 

 axes of the opposite segments of the calyx. Tlie middle nerves of the segments of the 

 corolla are in like manner continued below the point of cohesion to the real base of the 

 tube. 



The analogy of this disposition of vessels in the corolla of Goodenoviae to that of Com- 

 positae is obvious. To assimilate entirely the two structures, it is only necessary to suppose 

 a deeper division of the five primary vessels of Compositae, and a continuation of the tube 

 of the corolla below its apparent base to that of the ovarium. That this is its real origin, is 

 rendered not improbable both from the analogous structure now described in the family of 

 Goodenovia, and from the manifestly hypogynous corolla of Brunonia ; a genus in many 

 respects still more nearly related to Compositae, though differing in the disposition of the 

 vessels of its corolla. 



The more direct proof of this origin, derived from an examination of the surface Itself, 

 can hardly, perhaps, be expected where the parts are generally so small, and where, as I 

 conceive, the surface of the pericarpium in many cases depends less on that of the cohering 

 envelopes, than on the proper figure of the ovarium itself, as seems to be likewise the case 

 in Umbellatae. 



There are however a few cases in which this opinion respecting the origin of corolla in 

 Compositae may derive some additional support from the appearance of the surface of the 

 ovarium, as in Marshallia and Hymenopappui, in both of which genera, but particularly in 

 the former, it is marked with ten longitudinal striae, of which the five stronger are continued 

 into the five nerves of the corolla, the remaining five ending abruptly at the apex of the 

 ovarium. 



the 



