Verbena urticifolia

White Vervain
Inflorescence
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Asterids
Order:	Lamiales
Family:	Verbenaceae
Genus:	Verbena
Species:	V. urticifolia
Binomial name
Verbena urticifolia L.

Verbena urticifolia (White Vervain) is a herbaceous plant in the vervain family (Verbenaceae). It belongs to the "true" vervains of genus Verbena.

The Urtica-like leaves were the reason for the scientifiv name urticifolia.

White Vervain has opposite, simple leaves on thin, rigid, green stems. The leaves look similar to those of Urtica, which is the reason for the plant being named urticifolia. The small flowers are borne in spikes; they open in summer and unusually for this normally bluish-flowered genus are white.

It might be closest to a group that might include such North American species as V. lasiostachys or V. menthifolia, and the Common Vervain (V. officinalis) from Europe. As these, it is diploid with 14 chromosomes altogether. The relationship of the Swamp Verbena (V. hastata) to these species is more enigmatic; its evolution might have involved hybridization with the White Vervain or a related species in the past.

References

• Yuan, Yao-Wu & Olmstead, Richard G. (2008): A species-level phylogenetic study of the Verbena complex (Verbenaceae) indicates two independent intergeneric chloroplast transfers. Mol. Phylogenet. Evol. 48(1): 23-33. doi:10.1016/j.ympev.2008.04.004 (HTML abstract)