Christmas tree cultivation tractors, and shaper sheers. Mechanized planters, at a cost of about US$4,000, are not essential but a work-saving luxury for farmers. Farmers can purchase seedlings, the lifeblood of a Christmas tree farm, from nurseries. One farmer in Oregon purchased seedlings for between US$200–300 per 1,000 plants. The farmer, a wholesaler, sold his final products for about $20 each; after the cost of the trees and other expenses, a profit of $2–3 per tree. The best-selling species in the North American market are Scots pine, Douglas-fir, noble fir, balsam fir, Fraser fir, Virginia pine, and eastern white pine, although other types
Tree of virtues and tree of vices (c. 1310-1340). The nodes of the tree-diagrams are the Cardinal Virtues and the Cardinal Vices, respectively, each with a number of secondary virtues or secondary vices shown as leaves of the respective nodes. While on a tree of virtues, the leaves point upward toward heaven, on a tree of vices the leaves point downward toward hell. At the root of the trees, the virtues of "humilitas" "humility" and the vice of "superbia" "pride" is shown as the origin of all other virtues and vices, respectively. By this time, the concept of showing hierarchical concepts of medieval philosophy in diagrams also