OBSERVATIONS ON SOME OF THE PLANTS EXHIBITED. 
441 
OBSERVATIONS ON SOME OF THE PLANTS 
EXHIBITED. 
October 11, 1898. 
By the Rev. Prof. Geo. Henslow, M.A., V.M.H. 
Dahlias. —Mr. Henslow first called attention to the forma¬ 
tion of the Cactus Dahlia, comparing it with a small-flowered 
variety, somewhat resembling that first introduced from Mexico 
in 1798. Double Dahlias soon afterwards became the fashion, 
in which the corollas of the dish florets became tubular, enlarged 
and coloured like those of the ray. In the 1 Cactus ’ variety, 
they commence by being tubular ; then, flattening the petals 
they finally become curved the reverse way, thus acquiring the 
characteristic type of flower. 
Lobelia Cardinalis. —This was one of the earliest species 
introduced, viz. in 1629. Though it has no appearance of being 
a “ composite ” as the Dahlia, yet the structure of the essential 
organs so closely resembles that of the Composites that this 
genus may be regarded as probably approximating the ancestral 
form of that order. 
Pentstemon. —The flowers of this plant appear to be follow¬ 
ing those of Gloxinia and other irregular flowers ; in that, 
under cultivation, the corolla is tending to become regularly 
trumpet-shaped, and the stamens distributed around within it, 
instead of being located at one side, as in Labiates, Scro- 
phularinece, &c. 
Insectivorous Plants. —These were illustrated by Sarra- 
cenia purpurea, Cephalotus follicularis, Pinguicula cordata, and 
a small species of Nepenthes, or Pitcher-plant. The special 
feature which the lecturer called attention to was the close 
similarities of structure; as especially seen in Cephalotus and 
Nepenthes, both of these having similar shaped pitchers, with 
rigid circular rims, and lids as well as glands sunk in the inner 
surface ; yet they belong to orders widely asunder ; so that these 
resemblances cannot therefore represent any points of affinity. 
The interpretation appears to be that similar circumstances 
have evolved similar structures ; but what those conditions were 
are^quite unknown. Another point showing the extraordinary 
