i22 BorTHWICK—PRoOpP-ROOTS OF THE LABURNUM. 
smaller adventitious roots had been formed ; these, no doubt, 
served to support the tree and kept it supplied with water and 
food material from the soil. 
A striking example of such prop-roots on a laburnum tree 
was found by the Regius Keeper in the Royal Botanic Garden 
here, by whose permission I obtained the accompanying photo- 
graphs from which the illustration in Plate XXIV. is taken. The 
tree stands close into a hedge at the east side of the Rock Garden. 
The surrounding trees and shrubs make it impossible to obtain a 
full-sized photograph. The tree is very much forked, and at 
some time the stem has split from the lower fork down to the 
ground. There is no record of when this occurred, but, judging 
from the appearance of the wood, the split is an old one. The 
illustration gives a view of the base. It shows the split and 
decayed condition of the under part of the trunk. Two strong 
prop-roots have been formed, each arising in the angle of a fork 
some five or six feet from the ground. These roots branch and 
firmly anchor themselves in the soil around the base of the tree. 
An examination showed that the left half of the tree was kept 
erect principally by means of its prop-root. Unfortunately, 
during the storms of the winter of 1904-05, this portion of the 
tree was blown down. 
