AGRICULTURAL BULLETIN 
OF THE 
5TBAIT5 
AND 
FEDERATED MALAY STATES. 
No. 11.] NOVEMBER, 1909. [Voi, IX 
PEAT SOILS. ( Continued .) 
In Warming’s Oecology of plants he deals in chapter 84 with the 
formations in acid soils, but his observations are only made on those 
of cold climates. Formations like those of our so-called peat- 
formations occurring in the tropics seem to be rare, and no records 
have been made of them. 
The action of these soils on plants is, however, practically the 
same as in the temperate swamps, the main difference being that 
in the tropics the soil is composed of branches and trunks of large 
trees, while in temperate regions it is composed of smaller plants, 
bog-mosses, grasses and heaths. In the temperate regions a 
specially adapted flora has been produced to meet the demands of 
the peculiar soil, but in our limited areas, which seem to be of very 
modern age, there cannot be said to be a xerophytic flora developed 
from this soil formation as yet. 
The factors which go to make these soils xerophytic, although 
one would naturally expect them to be hygrophytic, are given as 
follows : — 
One of the factors is an increase in Transpiration, that is to say 
the plants exhale a greater quantity of water than they can afford, 
and even marsh plants specially adapted to grow in such localities 
may be forced to reduce their transpiration. Wet soil is cold, and 
therefore physiologically dry. We have no record of the temperature of 
these peat soils here, but this factor may affect the growth of rubber 
in such spots. Respiration is obstructed ( the soil being poor in 
oxygen), and the roots functional activity depressed. This is a 
serious factor, and that this is of the greatest importance to plants 
is shown by the occurrence of aerating roots to trees in the wet, 
swampy peat woods of the peninsula. Many of those who have had 
walk through such spots must have noticed the knees or projecting 
roots of certain trees rising a foot or more above ground in the from 
of cones. They are most abundant in the mangrove mud where the 
