Cercis canadensis aka Eastern Redbud

Eastern redbud, Cercis canadensis, is a deciduous tree in the pea and bean family, Fabaceae. It grows wild across eastern and central North America. Its range runs from southern Ontario and New Jersey south to Florida. It also reaches west to Texas and into northeastern Mexico. In the wild it grows in open woods, thickets, woodland edges, glades and rocky stream banks. It is the state tree of Oklahoma.

In gardens it grows 20 to 30 feet (6 to 9 metres) tall. It spreads about as wide or a little wider, often 25 to 35 feet (7.5 to 10.5 metres). Old trees on moist sites can reach 35 feet (about 10.5 metres). The short trunk splits into several large limbs close to the ground. Many trees have more than one trunk. The crown starts irregular and becomes rounded or flat-topped with age. Young twigs zigzag between the buds. The bark is dark brown and smooth at first. Later it breaks into scaly plates that show orange inner bark. The leaves are simple, alternate and heart-shaped, about 3 to 5 inches (7.5 to 13 cm) long. They turn yellow in autumn, though the colour varies from year to year.

The tree flowers in early spring, before its leaves open. Small pea-like flowers, about half an inch (1.3 cm) wide, appear in clusters of four to eight. They range from rose-pink to light purple. Many open straight from old branches and even the trunk. Flat pods 2 to 4 inches (5 to 10 cm) long follow. They ripen from green to dark brown and often hang on through winter.

Redbud grows in full sun or part shade. Trees in hot southern areas benefit from some afternoon shade. It prefers deep, moist soil that drains well. It copes with clay, sand, loam and chalk, and with acid or alkaline soil. It will not thrive in soil that stays wet. Once settled, it handles dry spells, but it looks better with summer watering. It resents root disturbance, so plant young trees in their final spot. Hardiness runs from USDA zone 4 to 9, with an RHS rating of H5. Trees from local seed sources are more likely to survive cold winters. It looks striking in groups. Bees and butterflies visit the flowers, and some birds eat the seeds. It is a larval host for Henry's elfin butterfly. Deer rarely bother it, and it tolerates black walnut.

The tree is often short-lived and its brittle wood can split at narrow forks. Pruning young trees for wide branch angles helps. Canker is the most serious disease. Verticillium wilt, leaf spots, coral spot and honey fungus can also strike. Insect pests include leafhoppers, treehoppers, scale, caterpillars, borers and Japanese beetles. Lawn herbicides can harm it.

The flowers are edible raw and have a pleasant sour taste. People add them to salads or pickle them, and the buds can stand in for capers. Young pods and young leaves may also be edible. The plant contains saponins, which are mildly toxic but largely pass through the body unabsorbed. Inner bark tea has served as an astringent folk remedy for diarrhoea and fevers.