The narrow, elongated flower spikes of verbena hastata
are 4 to 6 inches in length but bear only a small number of blooms at any one time, in a whorl; they open at the base of the spike early in the season, gradually moving upwards, over a period of several months. Plants produce several flower clusters, each containing between 1 and 8 spikes, and branching from the top of the upright, rigid stems, which can reach a height of 6 feet, though 3 to 4 feet is more common. The whole inflorescence often has a flat-topped outline. Stems are hairy, and square in cross-section.
Each flower has five violet-purple lobes, fused at the base to form a short tube, containing four stamens and a divided style. Flowers are surrounded by narrow, hairy green/ purple bracts, curving outwards.