field-research. It is conceded that on the basis of herbar- 
ium studies alone it will be difficult to clarify our under- 
standing of Hevea—its specific and varietal limitations, 
its history and its present distribution. This is perhaps 
one of the outstanding examples of the necessity for close 
correlation of field and herbarium studies and for close 
collaboration of the field and herbarium workers. We 
must guard against minimizing the fundamental impor- 
tance of herbarium methods and studies in handling the 
genus Hevea. Yet, at the same time, we should recognize 
that recourse must be made to methods not traditionally 
employed in systematics and to characters which, in some 
instances, can be appreciated only in the field. 
Some botanists believe that the genus Hevea may have 
had its origins in highland areas or on the slopes of moun- 
tains near the headwaters of the affluents of the Amazon 
and that the more primitive species and varieties are to 
be expected along the westernmost fringes of the range 
of the genus. In connection with such theoretical con- 
cepts, a study of Hevea in Colombia, as well as in Peru, 
holds especial interest, inasmuch as these countries have 
in their territories the highlands and slopes which would 
seem to have been most favorable for the early differen- 
tiation of the genus. 
II. 
As stated above, the present study is preliminary and 
provisional. I[t is not yet possible to present a considera- 
tion of all of the taxonomic entities of subspecific rank 
which have been found in Colombia. Therefore, the fol- 
lowing enumeration of the entities which have been found 
in the eastern regions of Colombia includes only three 
easily distinguishable varieties and no forms. An asterisk 
indicates a species or variety not yet known to occur in 
Colombia but known from localities so near the Colom- 
[5] 
