236 
PLANTS OF NORTHERN GUJARAT . 
and where, therefore, especially xerophytic conditions are present, we 
distinguish a Psammophvtic Formation. This occurs on (1) hills 
(dunes) of softer sand, and (2) the more elevated portions in river 
beds. The bed of such a river as the Sabarmati, if seen in cross section, 
would exhibit four levels ; — (a) the permanent stream or streams which 
change their position from time to time, (b) the ordinary bed, mainly 
devoid of vegetation, (e) a sort of higher level bed (not always present), 
and (d) gravelly bank with thorn scrub (not always present). It is 
where (c) is present that the psammophytes occur, (c) would only be sub™ 
merged on perhaps two days in every third year, and the sand being soft 
and of great depth surface water would be usually more or less absent. 
(1) Dunes: — 
These are dominated either by Sacckarvm Munja or by 
Crotalaria Burhia , and associated with these are Cy perns 
niveus, C. arenarius , C. conglomerate , and many members 
of the Sand Savannah. 
(2) River bed : — 
The usual association is Acacia Jacqucmontii , Leptadenia 
Spartium and Cassia auricula ta . 
These psammophytic associations may, with further study, have to be 
amalgamated in Sand Savannah ; but just as our flora shows the meeting 
point of the Perso- Arabian and Indo -Malayan floras, so our oecological 
conditions show the meeting point of the psammophytic formations of the 
desert with the psilophytic formations of central and western India. 
None of the associations and formations indicated in this paper can be 
regarded as finally settled. They must wait to take their place in the 
general oecology of the Indian continent as it is .gradually studied. 
Class 13. Mesophytes. 
Generally speaking the water content of the soil is so low throughout 
the greater part of the year, in our area, that meso phytic conditions are 
not met with, and nothing suggestive of the typical “ tropical jungle ” is 
found as a rule. We have noted only two examples of mesophytic asso- 
ciations, both quite exceptional and both occupying an area of negligible 
extent. 
The first, which we may call Mesophytic Bushland, occurs round the 
margin of a tank, neai; Kharaghoda, which is probably kept at a nearly 
constant level by means of a perennial spring. This association forms 
a belt about fifty yards wide all round the tank, the circumference of 
the latter being about half a mile. 
The following is a list of some of the plants 
