OF PLANTS CALLED COMPOSITjE. 267 



neaxly related to Compositse. It exists also in Ernodea, rss 

 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 lacinise as those of Compositse. A 

 similar disposition is observable in certain genera of 

 Solanacese, as Datura and Cestrum, though in these the 

 lateral nerves are more ramified, and their trunks generally 

 less distinct in the lacinise. It appears therefore that, in 

 adopting M. Cassini's theoretical expression for the vas- 

 cular structure of the corolla of Compositse, one pecu- [ss 

 liarity actually existing is lost.^ 



adhering part dilated into nectariferous processes ; or in tliose wliere, the seg- 

 ments of the caljx not being closely approximated, the coloured corolla is visible 

 in the interstices. In some species of Ooodenia, particularly G. decurrens and 

 bellidifolia, I find it practicable to separate not only the adhering calyx, but 

 also the tube of the corolla from the ovarium. In the tube thus separated 

 it appears that the lateral nerves, which preserve their parallelism to the 

 middle nerve nearly to the base of the segment, become more evidently divergent 

 below the point of adhesion, and in such a degree that the corresponding 

 branches of the neighbouring 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 seg- 

 ments of the calyx. The 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 Goodenovise to 

 that of Compositse is obvious. To assimilate entirely the two structures, it is 

 only necessary to suppose a deeper division of the five primary vessels of Com- 

 positse, 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 Goodenovio', 

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

 respects still more nearly related to Compositse, though diiJering in the dispo- 

 sition of the vessels of its corolla. 



The more direct proof of this origin, derived from an examination of the sur- 

 face 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 oases 

 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 Umbellatse. 



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

 of corolla in Compositse may derive some additional support from the appear- 

 ance of the surface of the ovarium, as in Marshallia and Hi/menopappns, in 

 both of which genera, but particularly in the former, it is marked with ten 

 longitudinal" strise, 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. 



' A still stronger objection to M. Cassini's definition is, that while its appli- 

 cation to Compositae is only hypothetical, it very nearly corresponds with the 



