Bladdernut family (Staphyleaceae)
Description: This native shrub is about 6-12' tall, branching irregularly and somewhat sparingly (especially in shaded areas). The trunk and/or larger branches have bark that is mostly grey and slight rough-textured, while smaller branches have bark that is smooth with longitudinal streaks of black and light grey. Young twigs tend to be smooth and reddish brown.
The opposite leaves are trifoliate; they have petioles about 1-5" long. Individual leaflets are up to 2½" long and 1" across; they are ovate in shape and finely serrated along their margins. Each leaflet has a rounded to wedge-shaped bottom and tapers to a tip that is short and slender; the upper surface of each leaflet is medium to dark green and hairless, while the lower surface is light green and pubescent. The terminal leaflet has a stalk (or petiolule) up to 1" long, while the 2 lateral leaflets are nearly sessile. Drooping clusters of flowers develop from the axils of the compound leaves. Each flower is about 1/3" long, 1/4" across, and bell-shaped; it is have 5 outer sepals, 5 inner petals, several stamens, and a pistil. Initially, both the sepals and petals are white; shortly later the sepals become light green or dull pink. The slender pedicels are a little longer than the flowers. The blooming period occurs during mid- to late spring and lasts about 2-3 weeks. Each fertile flower is replaced by a papery 3-celled seed capsule up to 3" long and 2" across; this capsule is obovoid or ovoid in shape with 3-angular lobes. Immature capsules are green during the summer, but they become light brown during the fall. At this time, the seeds can be made to rattle inside their capsule; there is a single seed per cell. The seeds are brown, smooth, and about ¼" across. The root system can form vegetative offsets from underground runners. Occasionally, colonies of shrubs are formed.
Cultivation: The preference is light shade to partial sun, moist conditions, and a fertile loamy soil with abundant organic matter. This shrub has few problems with pests and disease.
Range & Habitat: Bladdernut occurs in every county of Illinois and it is fairly common (see Distribution Map). Habitats include moist floodplain woodlands, mesic woodlands, riverbanks, and thickets. Bladdernut is typically found in deciduous woodlands where such trees as Sycamore, Silver Maple, Sugar Maple, American Basswood, and/or River Birch are present. Sometimes, this shrub is cultivated because of its attractive flowers, seed capsules, and leaves.
Faunal Associations: The flowers attract honeybees, bumblebees, Halictid bees (Halictus spp., Lasioglossum spp.), Andrenid bees (Andrena spp.), Syrphid flies, Dance flies (Empis spp.), and the Giant Bee Fly (Bombylius major). Most of these insects suck nectar from the flowers, although the Syrphid flies feed on the pollen and some of the bees collect pollen for their larvae. Another insect, Thrips quinciensis, has been observed sucking juices from Bladdernut (see Stannard, 1968). Additional information about floral-faunal relationships for this species is scarce. Apparently, White-Tailed Deer are less likely to browse on Bladdernut than other woody shrubs, although the reasons for this preference are unclear.
Photographic Location: A floodplain woodland in Vermillion County, Illinois. The flowers in the upper photograph are past their prime.
Comments: Bladdernut is the only member of its family in Illinois. When the flowers or seed capsules are present, this shrub is easy to identify – look for its drooping clusters of bell-shaped flowers or large papery seed capsules. In particular, the seed capsules are highly unusual in appearance and somewhat ornamental, reminding me of the papery husks that cover the berries of Physalis spp. (Ground Cherries), but the former are much larger in size and more angular in shape. The opposite trifoliate leaves of Bladdernut are also distinctive – other shrubs have alternate leaves, simple leaves, or compound leaves with more leaflets. Sometimes Staphylea trifolia is called 'American Bladdernut' to distinguish it from other shrubs in the Bladdernut family.