White vervain
Verbena urticifolia
''Verbena urticifolia'', known as nettle-leaved vervain or white vervain, is a herbaceous plant in the vervain family . It belongs to the "true" vervains of genus ''Verbena''.
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 from Europe. As these, it is diploid with 14 chromosomes altogether. The relationship of the swamp verbena to these species is more enigmatic; its evolution might have involved hybridization with the White Vervain or a related species in the past.
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 from Europe. As these, it is diploid with 14 chromosomes altogether. The relationship of the swamp verbena to these species is more enigmatic; its evolution might have involved hybridization with the White Vervain or a related species in the past.
