Photo by Gary Kurtz
Yellow giant hyssop typically grows between three to seven feet tall, with most plants reaching around five to six feet. The flowers are small and pale yellow, arranged in dense, vertical spikes that can be four to 16 inches long. Each individual flower is about 1/3 inch long. The leaves are opposite, thin, and coarsely toothed, somewhat egg-shaped with a rounded base, and attached to long stalks. They can be up to six inches long and three inches wide. Yellow giant hyssop prefers rich soil in a savanna (part shade) setting but can also tolerate full sun. It naturally occurs in meadows, along fencerows, in lowland woods, thickets, and upland deciduous woods. It thrives in moist to mesic conditions and can grow in both fairly dry and very wet locations. (SF)