of Cuphea ( Lythraceae ). 163 
Burkill (7). C. tetrapetala is also of wide distribution, 
occurring in the Andes from Mexico to Ecuador. The area 
of the remaining species is much more limited. Finally, we 
may observe that the centre of development of the section is 
in Colombia, which possesses no fewer than seven out of the 
ten species, four of them being endemic. 
Mexico. 
Central America. 
Colombia. 
Ecuador. 
Peru. 
Bolivia. 
Venezuela. 
Guiana. 
! West Indies. 
1 
C. setosa . . . 
,, rigidula . . 
... 
... 
... 
,, sordida . . . 
• • • 
„ hispidijlora . 
„ epilobiifolia . 
,, Buravii . . 
• • . 
• • • 
... 
,, Lehmanni 
„ tetrapetala 
... 
& 
... 
„ Bombonasae . 
• •• 
• • . 
„ tarapotensis . 
... 
£ 
Total . 
2 
1 
7 
2 
2 
1 
1 
■ 
1 
Biology. 
All the species of Heteranthus grow among rocks by the 
side of rivers, and are subjected to periodical inundation ; we 
find accordingly that they are all perennial and somewhat 
fruticose, as in such situations annuals would speedily die out 
unless provided with very special means of propagation. 
In connexion with the habitat should also be noticed the 
narrow linear or linear-lanceolate leaves so characteristic of 
the section. 
No observations have been recorded as to the pollination 
of any of the species, but it is abundantly evident from the 
structure of the flowers that they are entomophilous ; more- 
over, their position growing gregariously by riversides is 
a peculiarly favourable one as regards frequency of insect 
visitors, which in the dense forest crowd at the top of such 
M 2 , 
