Blue Vervain on Carpenter’s Prairie near my home in northeast Iowa. USA
There are Gray-headed Coneflowers in the background.
Verbena hastata (Blue Vervain)
Plant Info Also known as: Swamp Verbena
Family: Verbenaceae (Verbena)
Life cycle: perennial
Habitat: sun; wet fields, shores, ditches
Bloom season: June – September
Plant height: 1 to 6 feet
Flower: Flower shape: 5-petals Flower shape: tubular Cluster type: spike
Thin spike, 2 to 5 inches long, of blue to violet blue flowers. Individual flowers are a little less than ¼ inch across and have 5 petals fused at the base, forming a short tube. There are several spikes at the top of the plant. The spikes bloom from the bottom up.
Leaves and stem: Leaf attachment: opposite Leaf type: simple
Leaves are narrow, to 7 inches long and about 1 inch wide, with short leaf stems. The edges are coarsely toothed and the leaf base and tip are both pointed. The leaves near the base of the plant are sometimes lobed into 3 sections. Attachment is opposite. The stem is square, may be reddish or green, and may be somewhat hairy.
With a square stem and opposite leaves, Blue Vervain can be mistaken as a member of the Mint family, but it is not. It might also be confused with Hoary Vervain, but the flowers of Blue Vervain are smaller, its leaves are longer and narrower, and have short leaf stems. Hoary Vervain is also more partial to dry areas.