Of the Primary Divisions, the Dicotyledonous plants amount to 460.
The Monocotyledonous to 113
And of the Acotyledonous, in which Ferns are included, there are only 33 species.
It is a necessary preliminary, with reference especially to the first part of my subject, to determine whether this herbarium, which was collected in a period not exceeding two months, and in a season somewhat unfavourable, can 421] warrant any conclusions concerning the proportional numbers of the three primary divisions, or of the principal natural orders in the country in which it was formed.
Its value in this respect must depend on the relation it may be supposed to have to the whole vegetation of the tract examined, and of the probability of the circumstances under which it was formed, not materially affecting the proportions in question.
Its probable relation to the complete Flora of the country examined, can at present be judged of only by comparing it with collections from different parts of the same coast of equinoctial Africa.
The first considerable herbarium from this coast, of which we have any account, is that formed by Adanson, on the banks of the Senegal, during a residence of nearly four years. Adanson himself has not given the extent of his collection, but as he has stated the new species contained in it to be 300,[1] it may, I think, be inferred, that altogether it did not exceed 600, which is hardly equal to that from Congo. Limited as this supposed extent of Adanson's herbarium may appear, it is estimated on the most moderate calculation of the proportion that new species were likely to bear to the whole vegetation of that part of equinoctial Africa, which he was the first botanist to examine; allowance being at the same time made for the disposition manifested in the account of his travels, to reduce the plants which he observed to the nearly related species of other countries.
From the herbarium and manuscripts in the library of
- ↑ Fam. des Plant. 1, p. cxvi.
