Prunus nigra aka Canada Plum

Prunus nigra, or Canada plum, is a deciduous tree in the rose family. It grows in eastern North America, from New Brunswick to Manitoba. Its range extends south to Iowa, Ohio, and Connecticut. Wild trees grow in thickets, beside streams, and along woodland edges. They also grow in river valley soils and on limestone hills. The species is not native to Britain or Ireland.

The tree reaches about 30 feet [9 metres] in height. It sheds its leaves each year and flowers in April. Each flower has both male and female parts. Insects pollinate the flowers, and seeds ripen from August to September. The fruit measures about 1.2 inches across and holds one large stone. Its thick skin and sour taste can limit its appeal. Frost can improve the taste before harvest.

Canada plum grows in sun or partial shade. A sunny site helps it bear more fruit. It prefers moist loam that drains well but holds some water. It can also grow in sandy or clay soils. It accepts mildly acid, neutral, and mildly alkaline ground. Some lime suits it, but too much may cause chlorosis. Gardeners grow this species for fruit in Canada and the United States. It also has a place in woodland gardens and food forests. Aphids on the tree can harm nearby potato plants.

People eat the fruit fresh, cook it, or dry it. It can go into pies and preserves. The flesh is edible, but the seed carries a serious risk. PFAF reports prussic acid in the seeds and fatal poisoning in children. Remove the stones before using the fruit for food. The same source records past uses of bark infusions. People used the inner bark for colds and bark for stomach upset. These records describe traditional uses, not proof of safe treatment.

The leaves yield green dye, while fruit gives grey-green shades. People also used inner bark to help fix other plant dyes. The wood is hard, dense, and fine-grained. The tree stays too small for commercial timber use. Seed propagation needs two to three months of cold treatment. Germination may take as long as 18 months. Other propagation methods include layering in spring and summer cuttings.