Verbena Officinalis - Systematics

Systematics

One of the few species of Verbena native to regions outside the Americas, it is derived from the lineage nowadays occurring widely across North America. It might be closest to a group including such species as the White Vervain (V. urticifolia), V. lasiostachys or V. menthifolia, and perhaps the Swamp Verbena (V. hastata). As these, it is diploid with 14 chromosomes altogether.

Numerous local varieties have been described, some of them as distinct species or subspecies. The following are often accepted today:

• Verbena officinalis var. africana (= V. officinalis ssp. africana )
• Verbena officinalis var. eremicola
• Verbena officinalis var. gaudichaudii
• Verbena officinalis var. macrostachya (= V. macrostachya)
• Verbena officinalis var. monticola
• Verbena officinalis var. officinalis (= V. domingensis)

The Texas Vervain (V. halei) is sometimes included in V. officinalis as a subspecies or variety. But despite the outward similarity, biogeography alone strongly suggests there is really no justification to include this North American native here, and DNA sequence data agrees. Instead, V. halei seems to be closely related to V. macdougalii, perhaps with some interbreeding with the V. menthifolia lineage which might explain its Common Vervain-like traits.