410 The Philippine Journal of Science 1921 
is entirely dependent upon the culture of this tree, of which 
there are said to be several varieties. The tree at maturity is 
immense, with a trunk diameter at the base of 60 centimeters, 
and may attain a height of from 12 to 18 meters. The head 
shoots high above those of most fruit trees, is not very dense, 
and seems to provide a suitable amount of shade for the fruit. 
In Dao Kanong these trees are very commonly seen between 
citrus trees, but in the better Nakorn Chaisri groves they were 
not observed. The tree has an extensive fibrous root system 
which seems to thrive in wet soil, and a dense network. of roots 
and rootlets extends throughout the beds and even into the 
ditches. The interesting claim of growers is that the roots of 
the fruit trees feed upon the decaying roots of these trees; they 
also claim that the leaves fall into the trenches of water and 
decompose, and when smeared upon the surface of the beds 
provide an excellent fertilizer. 
There seems to be considerable difference of opinion among 
growers as to the extent to which intercropping and shading 
prove profitable. In the best Kao Pan pummelo groves of Na- 
korn Chaisri the growers do not make the error of excessive 
shading that often seems to be made elsewhere. In one of the 
best of these orchards it was interesting to note that, by the 
time the pummelo trees had attained the age of from ten to 
fifteen years and were nearly spread out over the surface of the 
beds, all betel palms and bananas had been removed, except the 
trees growing at the end of the beds or rows along particularly 
cherished walks extending through the heart of the pummelo 
orchard (Plate 8, fig. 1). In other groves the betel palms pre- 
dominated, even after the pummelos reached maturity (Plate 
8, fig. 2). In still another grove, betel palms were being newly 
planted between pummelos, after the latter were well grown. 
This might indicate that the betel palm was proving the more 
profitable of the two crops and was therefore supplanting the 
citrus. 
No accurate observation regarding the practice of shading and 
intercropping was obtainable from the growers, except that they 
consider some shade necessary for the first few years after the 
pummelo has been planted. The manager of one of the best 
groves takes out all betel palms after the pummelo trees have 
attained an age of from three to five years. In other groves 
the plantings were very much mixed, with mature banana and 
citrus trees growing side by side and with large coconut palms 
