Martin, I believe there are 2 different tree families called hackberry. Your Bird Cherry is classified as a 'prunus padus', along with other common cherry trees. The common hackberry is hard wood, and until recently was classified with the elms. However a few years back it was reclassifed in the hemp family 'cannabaceae', and genus 'celtis occidentalis' ( at least here in the middle part of the USA). This second mentioned hackberry is the tree often used in bow making, with characteristics similiar to elm--i.e. interlocking grain. It is fairly light in weight like a light weight ash; the trunk is usually very straight, and can reach 90 feet in height. This wood is creamy white with yellow streaks on occasion.