Blue Vervain (Verbena hastata)
Blue vervain is a native perennial of wet prairies, sedge meadows, thickets, and stream margins across the Upper Midwest. It typically grows two to five feet tall on stout, square, grooved stems. The leaves are narrow, lance‑shaped, sharply toothed, and arranged in opposite pairs, giving the plant a rugged, upright profile. Its defining feature is the flowering structure: slender, pencil‑like spikes that produce small blue‑purple blooms from midsummer into early fall, often continuing as other nectar sources decline.
Ecologically, blue vervain functions as a steady, mid‑ to late‑season resource for insects and birds. It supports several specialist and generalist herbivores. The common buckeye butterfly uses it as a larval host plant, laying eggs on the foliage, which the caterpillars feed upon. The Verbena bud moth (Endothenia hebesana) also develops within the plant’s reproductive structures, where its larvae feed on developing flowers and seeds.
The flowers attract a wide range of pollinating insects. Long‑tongued bees, including bumble bees and eucerine miner bees, regularly work the spikes. Short‑tongued halictid bees also visit, along with bee flies, thick‑headed flies, thread‑waisted wasps, and occasional butterflies. Soldier beetles are frequent visitors as well. This broad assemblage reflects the plant’s role as a high‑value nectar source during the late summer period when many other species have finished blooming.
Blue vervain also contributes to food webs beyond the growing season. Its seeds are eaten by several bird species, including song sparrows, swamp sparrows, field sparrows, slate‑colored juncos, and northern cardinals. In winter, the persistent seedheads continue to provide forage while adding structure to wetland and prairie remnants.
Sources:
Illinois Wildflowers – Verbena hastata
USDA PLANTS Database – Verbena hastata
Lady Bird Johnson Wildflower Center – Verbena hastata
Wagner et al., Caterpillars of Eastern North America (host plant notes)
Prairie Moon Nursery – Verbena hastata (ecology notes)
(Sumx)
