MINBU IN UPPER BURMA. 
15 
of the alluvial belt strongly discourage any attempt of such species 
to gain a footing thereon. The discouragement may be direct, by 
rooting out such plants as Zizyphus Jujuba y or such atrocious weeds 
as Tribulus terrestris or Martynia diandra ) or indirect by simply 
occupying the ground with crops. As may be imagined, the demarca- 
tion between the two zones is by no means a clear cut line, the two 
floras mixing to a certain extent where the influence of the Irawaddy 
fades away. The passage from the one vegetation to the other is of 
course still more gradual where the irrigated areas intervene. 
Excluding cultivated species, such as the various kinds of pulses 
and cucurbitaceous plants and cereal crops, etc., the number of 
Phanerogams collected is about 700 species, the number of Crypto- 
gams collected being so few as to be practically a negligible 
quantity. Nearly half the number of species were collected by 
Mr. Aubert and the writer and the remainder by the garden collector 
Shaik Mokim, who spent about five months in the district. On the 
not unreasonable assumption that these 700 species afford a fair 
representation of the vegetation of the district, an analysis of the 
collection should elucidate to some extent the distributional affi- 
nities of the flora of the district. 
As the differences in the vegetation of the three zones of the 
district roughly sketched above are sufficiently striking to impress 
even the most casual non-botanical traveller, it is evident that to 
consider the whole district as a unit and to analyse the collection in 
that light would lead to very misleading results. 
Accordingly the Arracan-Nwamadaung zone, the alluvial belt, 
and the desert zone collection have been separately analysed, and the 
results tabulated in percentages in the table given below. The fourth 
column shows the erroneous inferences as to the affinities of the flora 
of the district which might be drawn if the district were considered 
as a homogeneous unit. Geographically the district of Minbu comes 
within Major Prain’s Assam-Arracan sub-sub-area. Phyto-geographi- 
cally however only the westernmost portion of the district comprised 
by the Arracan-Nwamadaung zone can be considered as belonging 
to that sub-sub-area. The inclusion of the desert zone and alluvial 
belt plants would merely involve a purely fictitious additi on, in the 
case of the former of Deccan and African species, and in the case of the 
latter of African and cosmopolitan tropical species. The area and 
sub-sub-areas mentioned in the table are in the main sufficiently indi- 
cated by their names. It may not, however, be amiss to state more 
precisely the boundaries of the Deccan, Indus plain and Gangetic plain 
sub-sub-areas. They are the sub-sub-areas recognised by Sir Joseph 
