T ubiflorcB. 
153 
both) of the corolla; many of the Gesneraceae have very brightly- 
coloured flowers, which in some cases attain a considerable 
size. They are, again, more or less specialized in habit, with a 
distinctive external facies —comparable with the similar condition 
which characterizes certain other families, such as Ericaceae, 
Gentianaceae, Labiatae, etc. 
In regard to economy of megasporangia, the Gesneraceae are 
by no means advanced; the ovules are invariably numerous. The 
stamens are typically four in number, often with the staminodial 
remnant of a fifth ; an androecium of two stamens is the exception. 
The stamens are arranged didynamously, and the members of a 
pair tend to approximate, and in some cases actually fuse ; the 
possible significance of this will be referred to later. Relics of the 
ancestral regular flower with isomerous androecium are to be found, 
as in the case of Verbascum in Scrophulariaceae. These relics 
include the genera Ramonciia, Championia , Conandron and a few 
species of Niphcea and Bellonia —about a dozen species in all. 
Other relatively primitive features occur in Gesneraceae, rot merely 
exceptionally, but typically. The corolla is rarely, if ever, very 
highly specialized in shape or structure ; it is usually tubular, with 
a more or less open mouth. The ovary, moreover, is unilocular, 
in the sense which we have described as primitive ; and the fruit is 
not often very specialized. In the characters of the corolla, 
androecium and gynaecium, the Gesneraceae resemble Orobanchaceae 
very closely, and the latter family might reasonably be merged with 
the former. 
The unilocular ovary is one of the chief distinguishing features 
of Gesneraceae, and is practically without exception. The parietal 
placentae in the several genera display all degrees of protrusion 
towards the centre of the ovary-chamber; but in no case do they 
actually meet and so form a septum except in Monophyllcea and 
Loxophyllutn, comprising barely five species altogether. This mode 
of septation of the ovary has been referred to already; and its 
progressive action as an evolutionary tendency is recognizable in 
two large familes of the higher Tubiflorse, namely, in Gesnera¬ 
ceae, where the septation is barely realized, and, as we shall 
shall see, in Bignoniaceae, where a bilocular ovary is the rule. 
The Orobanchaceae and Gesneraceae, then, represent the ter¬ 
minal points of relatively short and approximated lines emanating 
from the scrophulariaceous stock. 
Before we leave the latter family we must refer to a striking 
tendency which distinguishes Gesneraceae sharply from all other 
