Plant of the Week: Yellow Giant Hyssop

The yellow giant hyssop brandishes dense, cylindrical flower spikes that resemble a miniature choir of cacti. The spikes emerge atop stout, square, branching stems and measure 4 to 16 inches long, depending on the size and maturity of the plant. Their 1/3-inch-long yellow-green flowers are short-lived, small in comparison to the rest of the plant, and don’t all bloom at the same time. At maturity, each flower is replaced by four one-seeded nutlets. Colonies are often produced from the root systems of yellow giant hyssop, but the plants don’t fare well during summer droughts. Bees, bee flies and butterflies suck nectar from the flowers, though the dense foliage also attracts predatory insects (wasps, spiders, ladybird beetles). Native Americans used the coarsely toothed leaves in compound mixtures to relieve poison ivy rash. Today, new populations are being found in association with oak savanna restoration—a dynamic that also exists on the eastern edge of Nature Boardwalk, where a new black oak savanna is being cultivated.

Common Name: yellow giant hyssop

Scientific Name: Agastache nepetoides

Family: Mint (Lamiaceae)

Native Status: throughout central and eastern North America

Plant Type: herbaceous flowering perennial (forb)

Height: up to 7 feet

Flowering Time: mid-summer to early fall

Flower Color: white to yellow-green

Interest: can be used in perennial gardens, attracts bees and butterflies