The annual rings are thinner compared to the alburnum.
It often happens after the circle of bark has been removed, a small portion of the inner bark adheres to the alburnum.
In some trees a difference in color exists between the outer part of the wood, the sapwood or alburnum, and the inner part, the heartwood or duramen.
When dried in open air, alburnum and duramen turn reddish brown.
The wood, used for medicinal purposes, consists of turnings from the workshop of the turner, and is a uniform mixture of the alburnum and duramen, but that used in medicine should consist only of the latter.