Abstract
In this thesis two things were attempted:
1. To establish how far exposure affects root wood histology in respect to:
a. Vessel diameter
b. Vessel length
c. Tibre length
d. Fibre wall thickness
e. Ray height
f. Ray width
g. Ray concentration
h. Vessel concentration
i. Parenchyma concentration,
2. To test experimentally the theory that any changes occurring were due to light.
The results of 21,640 measurements from root wood are:
1. Exposure affects root wood; the resultant wood histology tends to simulate that of stems.
2. Light could be a causal factor but the results of an experiment to test this hypothesis proved inconclusive.