Use as a dye
This is a superb resource and a harvest will do no harm to a healthy
The young leaves make a reddy-brown, mature leaves a darker, but warm
brown, and the nuts (husk and all) give a black-brown.
Boil the walnut plants for an hour and use the liquid by simmering for
up to an hour. The wool will look darker in the dyebath than once it is
washed, so leave it a bit longer than the colour you require to pick up
the hue you desire.
Although this is known as the native Walnut, the name is though to come
from the old English word wealhhnutu, meaning literally 'foreign
nut'. (This has the same root as Welsh - meaning Foreigners).