xii DESIDERATA. 
of the working botanist at home. — So in regard to the specimens 
themselves, an isolated leaf, a separate flower, or even a fruit 
are insufficient alone to determine the species. A perfect dried 
specimen includes foliage, flower, and fruit, with notes on size, 
colour, and other points which it cannot indicate ; a flowering 
branch with foliage is generally sufficient to identify a well 
known species, but the description of a new one is always 
imperfect, and often wholly inefficient without the fruit. Where 
that is too bulky or too succulent to be laid in with the flower- 
ing and leaf specimens dried flat, and if preserved in spirits, or 
dried without pressure, portions of the foliage should be inva- 
riably attached to it as the sole means of future identification 
with the corresponding flowering specimen. 
In a purely botanical and systematic point of view, any 
plants not enumerated in the following Flora, and more espe- 
cially those mentioned as imperfectly known would be the most 
valuable. Palms, and other large Monocotyledons, bulbous-rooted 
and smooth thick-leaved plants of the same class, aquatic plants 
in general, whether floating or immersed, and cryptogamic 
productions have hitherto been but seldom collected. So it is 
also with Artocarpee and other large-fruited trees, Cucurbitacee, 
and all plants which require a little extra care in drying, and a 
little extra ingenuity in gathering, such specimens as may supply 
the requisite information. 
To the geographical Botanist, Western Tropical Africa is of 
peculiar interest, as being (next to the Arctic Regions), the 
point where the greatest number of species or forms belonging 
to the Eastern and Western hemispheres are found to meet. 
It may be consequently expected to furnish many valuable data 
respecting the migration of species, either naturally or by 
human aid, and the circumstances which determine the regions 
of analogous forms among endemic species. 
The most important information we have on this subject is 
summed up in Brown’s justly celebrated Appendix to Tuckey’s 
Congo. The facts since collected tend still farther to confirm 
the supposition that the greater number of cultivated plants 
have come to the Negroes of Western Africa from the East, 
iia ain 
