1. Notes on the specimens of Hevea in the 
De Candolle Herbarium 
Although there are larger and more comprehensive 
collections of Hevea in several European and American 
herbaria, it is true I think, that one of the most uniquely 
significant is contained in the De Candolle Herbarium 
in the Conservatoire Botanique in Geneva. 
The intensive and extensive field studies and collec- 
tions which Richard Spruce carried out a century ago in 
the Amazon Valley laid the first solid foundation for our 
understanding of the genus of the commercial rubber 
tree. Bentham’s critical treatment of Spruce’s material 
set the pace for later taxonomic work in the group. But 
the first attempt at a monographic synopsis of Hevea was 
that of Mueller of Aargau, working in Geneva. 
Notwithstanding the fact that Mueller had access to 
a number of collections of HZevea in the Delessert Her- 
barium in Geneva and in other European institutions, 
we may regard the specimens preserved in the De Can- 
dolle Herbarium as representing the core of his study 
material. ‘These were, in large part, the basis of his treat- 
ment of Hevea in De Candolle’s Prodromus 15, pt. 2 
(1866) 717-719. Partly because of this association, the 
specimens and Mueller’s handwritten annotations which 
some of them bear are worthy of special attention. Few 
of the specimens are rare; on the contrary, most of them 
are Spruce collections and are rather well distributed 
amongst the major herbaria of the world. This in itself 
is an additional reason for a close examination of those 
sets which have been, in a way, authenticated by the 
work of that great master of the 7uphorbiaceae. 
The arrangement of the species in the De Candolle 
Herbarium follows the order of their publication in the 
Prodromus. Thus, the material of Hevea can be found 
[ 22 
