293 
is very characteristic, more so than the trees, consisting of Ccesalpinia 
Nuga, Gapparis sepiaria, and, very largely, of Pisonia aculeata. In 
the more muddy soil which occurs on the outskirts of the mangrove- 
swamps other shrubs and creepers occur; such as Leea sambucina with 
stilted roots like the mangroves, Cynometra ramifiora, Hibiscus tiliaceus, 
Flagellaria indica, Mucuna gigantea, remai’kably common, Sarcostigma 
edule, Plecospernum andamanicuni, Antitaxis calocarpa, Salacia prinoides, 
which extends also into the swamp proper, Acrostichum scandens, etc • 
Not infrequent in such situations, when there is no high forest over¬ 
head is Vitex Negundo which is particularly common on Little Coco. 
In this muddy tract the tall trees remain much the same as in the 
drier area just behind the beach. Farther inward the vegetation is that 
characteristic of a true mangrove swamp, Bruguiera, Ceriops, Bhizophora, 
Aegiceras, Avicennia. The Avicennia, strangely, does not appear to be 
common in many of the creeks, though there is one creek, on the east 
side and near the south end of Gireat Coco, in which it is the prevailing 
tree; except indeed for a few Bruguiera gymnorhiza trees along the 
open channel of the creek, the whole swamp consists of Avicennia 
officinalis with thousands of its curious roots protruding through the 
mud and water as described already in a former paper (/. A. S. B. 
vol. lix, p. 272) ; considering the situation and loose structure of these 
roots, which are of the consistence of solah-pith, there seems every pos¬ 
sibility that they are concerned in the process of transpiration ; the large 
area covered by the roots of each tree must also afford great stability to 
a species which affects, as this one does, the situation of the mangroves 
without having their stilted roots. In this particular swamp each tree 
was loaded with the climbing form of Salacia prinoides and, as the latter 
happened to be in flower at the time of the visit, the foetid nature of 
the atmosphere experienced may be imagined. 
Between the headlands, in most cases, a choked-up creek is to be 
found ; generally this extends but a short way into the jungle, though 
sometimes it winds about on the level ground for a considerable distance 
as a mangi-ove-swamp. In two places the creeks on Great Coco are 
apparently open at all times to the tide ; the chief creek is that which 
debouches at the north end of the island. There are no open creeks in 
the other two islands, though at the south-west corner of Little Coco 
what has been a creek of considerable extent is now converted into 
a large lagoon by a broad bank of sand having been blown and beaten 
up by the south-west monsoon into a Arm embankment across its former 
outlet. 
On the ridges the trees are much the same, as to species, as on the 
lower ground, except that the Miliusa which is common below is scarce 
103 
