106 DR. HOOKEE A^D D». THOMSON'S PBiECURSORES 



Praecursores ad Floram Indicam. — Balsaminese. By J. D. Hooker, 

 M.D., F.E.S., L.S. &c. and T. Thomson, M.D., F.E.S., L.S. &c. 



[Read June 16th, 1859.] 



This Order, as is well known, attains its maximum development 

 in India, and it there presents a vast assemblage of forms, all but 

 one of which strictly belong to the genus Impatiens. 



It is often the case that when a genus is in a striking degree 

 local, its species are to a considerable extent well marked and 

 easily defined : such, however, is not the case with Impatiens ; for 

 it would be difficult to indicate another genus in the vegetable 

 kingdom, presenting amongst its species so many and such different 

 modifications of structure, and of which the species are so univer- 

 sally and so excessively prone to vary. 



We commenced the study of the genus several years ago, with 

 nearly 100 species, fully 2000 good specimens, from all parts of 

 India, and engravings or original coloured drawings, with analyses, 

 of upwards of fifty. On surveying these materials for the first 

 time, we were struck no less with the prominence of the natural 

 groups into which most of the species appeared to arrange them- 

 selves, than with the marked contrasts in the form and colour of 

 the floral organs of many of the species ; and the accessibility and 

 apparent feasibility of these characters were so obvious, that we 

 congratulated ourselves on the prospect of making natural and 

 well-defined groups of the majority of the species at any rate. A 

 little further examination of these seemingly objective groups 

 sufficed to dispel the illusion; and after three different earnest 

 attempts to master the genus, at intervals of several years, and 

 with the aid of many more specimens received since we commenced 

 the task, we have now just risen from what must be for the present 

 the final effort, with a feeling of great dissatisfaction with the 

 results obtained, whether as to grouping or limiting the species. 



There are only two obvious and well-limited divisions of Impa- 

 tiens : — 1. The ScapigercB, with tuberous perennial rhizomes (appa- 

 rent roots), from which all the leaves immediately spring, and 

 long scapes with short terminal racemes of flowers ; and 2. The 

 Caulescentes. Were both these divisions comprehensive, the 

 facility of recognizing them would have materially aided the 

 systematic study of the species ; but it is not so : the acaulescent 

 consists of five (or perhaps but three good) species, and is so 

 singularly confined in geographical area (the western peninsular 



