Physocarpus opulifolius.commons.wikimedia.org (Accessed 5/2014).

Physocarpus opulifolius is a shrub to 3 m tall, bark on small, woody twigs dark red-brown, on older stem bark shreds in strips, pale and dark brown. 

Leaves alternate, 3-5 lobed to unlobed, to 7 cm long, about half as wide, lobe tips blunt, base blunt to shallowly lobed, margin irregularly toothed, dull, medium green above, paler below. 

Flowers white to pinkish, to 1 cm wide, shallowly cup-shaped, 5 petals, stamens numerous; flowers on thin individual stalks 1-2 cm long, along twig tip; inflorescence terminal, densely umbrella-shaped, to 6 cm wide, on a stalk grading into twig tip, May-June. 

Fruit dry, inflated, 3-5-lobed, to 1 cm long, greenish to reddish with several very small, brown seeds, Sept.–Oct. 

Wetland status: FACW. 

Frequency in NYC: Very infrequent. 

Origin: Native but mostly north and west of NYC. 

Habitat: Planted in restorations, or escaped from cultivation. Does well on moist fill with Eastern cottonwood. Appears tolerant of light shade. Prefers soil pH 6-8.5. Normally found along open shores, swamp margins, streamsides, wet shrublands. Tolerant of flooding, drought, soil compaction. Moderately tolerant of salt (Hightshoe 1988).