Scalp hair is the best match for an initial donor source as it will have the same diameter, curl, color match, and growth characteristics. Beard hair generally is thicker, darker, and has more curl than scalp hair. Curly hair gives the illusion of greater density (ie covers more exposed scalp). This is advantageous when the beard and scalp hair are a close color match. Obviously, if light scalp hair is mixed with dark beard hair, the transplanted scalp will look odd, and not a good choice. However, when a close match exists, beard transplant donor sites heal well and most men also don't mind shaving less neck beard hair in the morning!
The choice of donor hair is the scalp (back or side of the scalp). But if the scalp donor is not adequate then one may use beard grafts in combination with the scalp hairs mainly in the back area or the crown area. Front area should be generally treated with scalp grafts only.