Although small, the yellow spring flowers of Oregon grape draw bees in moist, partially shaded yards, wild areas and mountain forest areas. Native to the Pacific Northwest, Oregon grape does well in wet moderate-to-cool climates.
By contrast, rabbitbrush flourishes in areas Oregon grape would find very inhospitable. Rabbitbrush favors hot dry areas, becoming leggy only when given excessive water. Yellow flowers appear among blue-green foliage in the spring.
Nicknamed "the rose of Japan" Kerria sends out long arching branches ornamented with vivid orange-yellow flowers in mid-to-late spring. Kerria is suited to moderate-to-warm conditions and will bloom in dappled shade or partial sun.
A non-woody perennial, tickseed dies back in cold winters, reviving in spring to provide abundant flowers in shades of yellow running from creamy to golden. Tickweed can be grown in hardiness zones 5 to 9 and prefers full sun.
Depending on region and growing conditions, varieties of these natives will differ, although some type is likely available in hardiness zone 3 to 9. Aster (Aster) petals range from white through blues and purples, with consistently yellow centers. Rudebekia hirta goes by the nicknames of black- or brown-eyed Susans. Sunny conditions are more important than temperature ranges for this hardy native. Likewise, goldenrod (Solidago) flourishes in sunshine, whether on the edges of forests and fields or cultivated in gardens. Technically, none of these fits the description of shrub, but all grow in bushy profusion throughout the summer.