258 
FLORA OF THE SUNDRIBUNS. 
Another species which may have been thus introduced, but which is more 
probably an instance of introduction by the sea, is Caesalpinia Bondu- 
- a shrub plentiful behind Andaman sea-beaches The remainder 
of the sea-face species are probably unequivocal instances of sea- 
introduction, so that two-thirds of the sea-face flora as against only 
one half of the swamp-forest flora is of truly littoral type. A few 
of the species^ like Derris scandens, Dolichandrone Rheedei^ Bar^ 
ringtoma racemosa, Acanthus tlicifoUuSy Crinum asiaticum are to 
be found within the swampy islands, but the majority of the sea-face 
plants that are also to be found in the swamp-forests are there strictly 
limited to the banks of the large rivers. Such species are Vitis 
trifolia^ Desmodium umhellatum^ Vigna luteola^ Dalbergia torta, 
C^salpinia Nuga^ Ipomosa illustris^ Clerodendron inerme^ Sesuvium 
Portulacastruniy Martscus albescens^ Oryza coarctata. A number 
of the sea-face plants, however, that find the conditions offered by 
the swamp-forests uncongenial, recur on the sites of abandoned settle- 
ments, along the northern fringe of the forests, or in the existing 
clearings; examples that may be cited are Naravelta zeylanica, 
Capparis sepiaria^ Thespesia populnea^ Crotalaria verrucosa and 
C. Saltiana^ Ecythrina indica^ Trewia nudifiora^ Ficus Rumphii, 
Pycreus polystachyus, Pimbristylis ferruginea^ Zoysia pungens ; the 
last named is also met with at the upper margins of newdy-formed 
mud-banks not yet afforested by swamp-forest species. One sea-face 
species, Saccharum sponfaneum, also occurs in the grassy savannahs. 
Abandoned Sites.— In places where there are vestiges of former 
occupation by salt-smugglers, or dacoits or where, as at Jatta, a settled 
population had at some former ‘time obviously existed, a number of 
characteristic species are to be found ; these have been fully dealt with 
in a former chapter and, as might be expected from the topography and 
the physical conditions of such localities, they do not include any species 
likely to have been introduced by the sea. Nor can rivers be held 
directly responsible for the introduction of any of the species. Two for 
which this means of dispersal is conceivable are Crotalaria verrucosa 
and Derris scandens, but of these the first is more likely, in places of 
the kind, to have been inadvertently introduced by man as a fitld-weed ; 
the Derris^ though doubtless brought down from Upper India or 
Assam by rivers in the first instance, has more probably been carried 
to such spots by wind from the neighbouring swamp-forests. As regards 
wind-agency too the number of introductions is very small, for even 
if we consider Derris scandens 2.S here wind-introduced, we 
have only five species for which this means of dispersal is at all 
likely, the other four being Vernonia cinerea, which is just as likely 
to be an inadvertently introduced weed ; Dioscorea pentapkylla, 
