Flower:

Droopy clusters of 5 to 12 stalked flowers at the tips of 1-year-old branches, emerging with the leaves in spring. Flowers are bell-shaped with 5 white petals flaring at the tip, ¼ to ½ inch long. Protruding from the tube are 5 white stamens with yellow-orange tips and a greenish-white, 3-lobed style somewhat longer than the stamens. The sepals around the base of the flower have 5 oblong lobes that are pale green to reddish and nearly as long as the petals.

Leaves and stems:

Leaves are opposite, compound with 3 leaflets on stalks up to 5 inches long. Leaflets are 2 to 4 inches long, 1 to 2½ inches wide, egg-shaped to elliptic with an abrupt taper to a sharply pointed tip. Edges are finely serrated. The upper surface is bright to dark green and hairless or hairy along the veins; the lower surface paler and hairy. The lateral leaflets are stalkless or nearly so with the terminal leaflet long stalked; stalks are hairless to sparsely hairy.

New twigs are hairless, reddish to green becoming brown the second year. Older bark is gray-brown with distinctive pale fissures or flecks, smooth or somewhat rough and flaking with age. Stems are up to 2 inches diameter and may be single but usually multiple, new shoots arising from root suckers and forming thickets.

Fruit:

Fruit is an inflated, papery pod 1 to 2½ inches long, oval in outline with 3 pointed lobes, each section containing up to 4 seeds. Seeds are shiny brown, about ¼ inch long, and eventually become loose and rattle around inside the pod when shaken.

Notes:

Bladdernut is a large shrub of deciduous woods and floodplain forest and reaches the northwest edge of its range in Minnesota. When flowering or especially fruiting it is not easily mistaken for any other shrub. The leaflets may resemble leaves of some other shrubs, such as Prunus, but the combination of long-stalked, opposite leaves compound in 3s, serrated leaflets hairy on the underside, and older bark that is gray-brown with pale streaks or fissures should help distinguish Bladdernut from other shrubs even when flowers or fruits are not present.