12 Mr. Don’s Observations on the 
been noticed in the figures and descriptions of the plant which have recently 
appeared in the Botanical Magazine and Register. I am inclined to think 
that -Tropeolum dipetalum of the Flora Peruviana will prove to be a second 
species of this genus, and it is possible that Tropceolum may include the types 
of other genera, when the nature of the fruit in the different species becomes 
better known. 
The genus Tropeolum was originally included by Jussieu among his Gerania; 
but he afterwards changed his opinion somewhat, in considering it the type of 
a distinct group; still adhering, however, to his former views of its affinity, 
by continuing to place it next that family, in which he has been followed by 
Richard, DeCandolle, Auguste de Saint-Hilaire, and other botanists of deserved 
eminence. The Tropeolec differ in many important points of structure from 
the Geraniacec, particularly in the want of symmetry between the stamina 
and other parts of the flower; in the structure of their stigmata ; in their 
thick, fleshy cotyledons, with the short radicle placed between their lobes; in 
the conspicuous plumule, by their axillary flowers; and finally in the absence 
of stipules. They have always appeared to me to be more nearly related to 
the Capparidece than to any other family, being principally distinguished from 
them by the quinary arrangement of the petals and lobes of the calyx. In the 
hypogynous insertion and indefinite number of the stamina, in the inequality 
of the petals, pendulous ovula, thick, fleshy cotyledons, absence of albumen 
and stipules, and in the axillary inflorescence, both families agree precisely. 
In the Tropeolee there is likewise an evident indication of the pistilliferous 
column so conspicuous in Capparidee. On comparing this family with the 
Hippocastanee many striking analogies present themselves ; such, for example, 
as the quinary arrangement of the petals and lobes of the calyx, the absence 
of symmetry between the stamina and other parts of the flower, in the struc- 
ture of the ovarium, which in both is formed by the union of three, mostly 
monospermous carpels, in the absence of albumen, in the structure of the 
embryo, having large, thick cotyledons, which become united as the seed 
advances towards maturity, with a conspicuous plumule, and a disproportion- 
ately small radicle. It is interesting to trace these remarkable coincidences 
in structure between families, which apparently have no real affinity together : 
for, although the Hippocastanee are chiefly distinguished from Tropeolee by 
