Prunus apricots, of cherries, and of plums, all of which have cultivars developed for commercial fruit and nut production. The almond is not a true nut, the edible part is the seed. Other species are occasionally cultivated or used for their seed and fruit. A number of species, hybrids, and cultivars are grown as ornamental plants, usually for their profusion of flowers, sometimes for ornamental foliage and shape, and occasionally for their bark. The Tree of 40 Fruit has forty varieties grafted on to one rootstock. Species such as blackthorn ("Prunus spinosa"), are grown for hedging, game cover, and other utilitarian
Prunus ursina It is usually present in too small a quantity to do any harm but any very bitter seed or fruit should not be eaten. Consumption of small quantities of hydrogen cyanide stimulates respiration and improves digestion. Excessive consumption of the toxin can cause respiratory failure and death. "Prunus ursina" fuits better in full sun but is still successful in partial shade. The tree will form suckers if its shallow roots are damaged. Among the pests that affect the "prunus" genus is honey fungus. the seed requires 2–3 months cold stratification in order to germinate. Prunus ursina Prunus ursina (bear's plum,