WSNLA Washington State Certified Professional Horticulturist Practice Exam

The correct name for Physocarpus opulifolius 'Diablo' is indeed Diabolo Ninebark. This plant is notable for its distinctive dark reddish-purple foliage, which sets it apart as an ornamental shrub in landscapes. Ninebark, a member of the Rosaceae family, is well-regarded for its attractive bark and flowers in addition to its foliage color, making 'Diablo' a popular choice among gardeners seeking visual interest throughout the growing season.

The other names listed do not refer to this specific plant. Red Twig Dogwood refers to a different genus and species, known for its vibrant red stems in winter. Summersweet is a common name for Clethra alnifolia, a flowering shrub appreciated primarily for its fragrant white or pink blossoms. Maiden Grass is a type of ornamental grass, specifically Miscanthus sinensis, which does not share the same physical characteristics or genus as Ninebark. Understanding these distinctions helps in accurately identifying and utilizing landscape plants.