Flower:

A thick spike cluster 1 to 6 inches long of light blue to violet tubular flowers. Individual flowers are about 1/3 inch long with 4 long stamens. The lower lip of the tube is longer than the upper lip, has a wide center lobe and 2 small side lobes. The spikes are usually tightly packed with flowers but sometimes there are gaps in the spike (interrupted). Not all of the flowers in the spike are in bloom at one time. The color of the cup-like whorl of sepals (calyx) holding the flower ranges from green tinged blue-violet to deep blue-violet. One plant may have multiple spikes.

Leaves and stem:

Leaves are up to 4 inches long and 2 inches wide, with a rounded base, pointed tip, coarsely toothed edges and a short stem. The underside of the leaves are grayish, covered with fine hairs. Like all members of the Mint family, the stem is square; it may be slightly hairy as well.

Notes:

Blue Giant Hyssop often grows in clumps and is a favored plant of bees. The leaves smell like anise when crushed. A similar plant is Purple Giant Hyssop, which is distinguished by the green calyx holding each flower and green underside of its leaves. Purple Giant Hyssop is also generally a taller plant.