Genus Agastache
Mint Family (Lamiaceae/Labiatae)

Horsemint or Giant Hyssop

Horsemint or Giant Hyssop
(Agastache urticifolia)

When not in bloom, this plant looks very much like a stinging nettle. The stem is hollow and square in cross section, and the leaves are opposite. In fact, the species name urticifolia means "nettle-like foliage".

However, the flowers are very different on the two plants. The flowers of the stinging nettle are tiny and inconspicuous. They grow in the axils of the leaves, all along the stem.

Horsemint flowers

The horsemint flowers are also quite small, but they grow in a dense spike (about 2 inches long) at the top of the plant. The petals are pale pink or white, and each tiny flower in the spike is surrounded by a lavender colored calyx (5 united sepals).

The plant has a strong minty aroma.

Look at a photo of a stinging nettle plant.