110 
PACIFIC SCIENCE, Vol. XXI, January 1967 
Fig. 4. The swamp fern, Acrostichum aureum, in the foreground; behind, a marginal zone of Trichoon 
karka, with intermixed coconut palms. 
Ponape, Kusaie, the Marianas, or the Marshall 
Islands. Many other mangrove formation plants, 
common enough in Malaysia and the Philip- 
pines, do not occur anywhere in Micronesia 
(e.g., Aegiceras, Kandelia, other species of 
Rhizophora ) . Xylocarpus granatum occurs else- 
where in Truk, but I did not find it in Romo- 
num. 
Rhizophora stylosa Griff, has been found in 
Ponape ( Stone 1773) and in Guam ( Stone 
4437) and probably occurs in Truk also. 
The mangrove formation of Romonum is on 
the whole rather poorly developed. The one 
extensive area is on the southern side of the 
island, from about the middle to within a few 
hundred yards of the east end. Small parts of the 
periphery have been converted to taro {Colo ca- 
st a) or Cyrtosperma plots. The larger central 
area of the swamp is composed of scattered and 
fairly small individuals of the various species, 
seldom over 10 ft high, interspersed with clumps 
of Acrostichum. 
Freshwater Swamps 
All of these are now to some extent planted 
with taro or Cyrtosperma , but they also include, 
to quite varied extent, various other species. 
Some swamps have been essentially cleared of 
vegetation, which has then been replaced by the 
cultivated aroids. Others, perhaps abandoned 
at various times of earlier cultivation, have be- 
come overrun with "weedy” species or with in- 
vading native elements. In time the freshwater 
swamp trees, Banin gtonia racemosa and Met- 
ro xy l on ami c arum, become a conspicuous fea- 
ture (Fig. 6). Also, the periphery of such 
swamps is constantly undergoing slight changes, 
depending on the adjacent area; advancing on 
