Viburnum lentago aka Nannyberry

Nannyberry, Viburnum lentago, is a deciduous shrub or small tree in the family Viburnaceae. Other common names include sheepberry, wild raisin and sweet viburnum. It is native to central and eastern Canada and the northern and eastern United States. Its range runs from Hudson Bay and Manitoba south to Georgia and Mississippi. In the wild it grows in low woods, at swamp edges and along stream banks.

In gardens it usually reaches 10 to 18 feet (3 to 5.5 m) tall and 6 to 12 feet (2 to 3.5 m) wide. Trained to a single trunk, it can make a small tree up to 30 feet (9 m). The plant has several upright stems with arching branch tips. It becomes open and leggy at the base with age, and it suckers freely. The bark is dark grey to black and breaks into small blocks. Young stems are smooth and brown.

The leaves are opposite, simple and ovate, about 2 to 4 inches (5 to 10 cm) long. They are glossy dark green, finely toothed and end in a long, drawn-out point. The leaf stalk has a wavy, winged edge, which helps with identification. Autumn colour varies from dull yellow-green to orange, red or purple. Some sources call it unreliable.

Flat-topped cymes of small creamy white flowers open in May, sometimes into June. Each cluster is 3 to 4.5 inches (8 to 11 cm) across and has no scent. Oval drupes about half an inch (1.3 cm) long follow in pendulous clusters. They pass through green, yellow and pink before ripening blue-black in autumn. The fruit often lasts into winter. Rotting fruit gives off a smell like wet wool.

Nannyberry is hardy in USDA zones 2 or 3 to 8, and the RHS rates it H7. It grows in sun or part shade, in moist but well-drained soil. It tolerates clay, loam, sand and chalk, and copes with drier sites and urban conditions. It grows larger in open spots than in shade. Prune right after flowering, because next year's flower buds form in summer. Remove root suckers unless you want it to spread.

Gardeners use it for tall hedges, screens, shrub borders and naturalised or woodland plantings. Birds and other wildlife eat the fruit, and butterflies visit the flowers. It is a larval host for the spring azure butterfly. Deer damage it only mildly. The heavy, hard wood smells unpleasant and has no commercial value.

Serious problems are rare. Powdery mildew can appear, especially in shade, and leaf spot occurs at times. Other possible troubles include mealybug, aphids and viburnum beetle. Phytophthora, honey fungus and grey mould are also listed. The ripe fruit is edible raw, cooked or dried, and goes into jams and jellies. It is sweet but thin-fleshed around one large seed, and some say it is best after frost. The ASPCA lists the plant as non-toxic to dogs, cats and horses. The RHS, however, labels the fruit ornamental and not for eating.