Vervains
What are they?
Although there are strong similarities in the flowers, the vervains are a rather variable group of plants, varying from low, trailing or creeping species to twiggy, upright ones. The flowers have tubular bases, opening at the mouth with five lobes, usually arranged as two lobes at the top and three at the bottom; the flowers somewhat resemble larger versions of the flowers of thyme. Vervains form their own family, but are considered to be quite closely related to the labiates (dead-nettles and their allies); the family has many more species in the tropics and a number have been introduced to the UK as garden ornamentals.
Where are they found?
Our one native species may be found in dry, open places, while the introduced species occasionally crop up where garden waste has been dropped or dumped.
Identification
Vervains rather resemble the labiates in their square stems and opposite leaves, but they are classified as different from each other by virtue of small details of the ovary and the stigma within the flower. The flowers of vervains are all rather similar to each other, so identification to species is best done using features of the leaves and the structure and shape of the overall flower heads.
Common Vervain Verbena officinalis
Probably an early introduction in Neolithic times. Widespread, but nowhere common, favouring mostly chalky soils and liking open, sunny sites that dry out in summer. May be found in a wide range of grassy places or even as a weed on walls and in urban places. Flowers July to September. Plants are very variable, from 10cm to 80cm in height and have thin, wiry stems that are easily overlooked except on the largest of plants. Lower leaves are deeply lobed but upper leaves are smaller and may be toothed on the edges but not lobed. Flowers appear a few at a time on spikes that progressively elongate throughout the flowering season.
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Argentinian Vervain Verbena bonariensis
Introduced from South America as a garden ornamental. A very popular garden plant for its ability to attract butterflies. At one time considered a half-hardy annual, but more mild winters in recent years have allowed the species to flourish and self-seeded plants are commonly appearing in urban environments. Flowers July to September or until the first frosts. A rather wiry, spindly plant that may grow to a metre or more in height. Rounded clusters of vivid purple flowers continue throughout the summer. Leaves narrow, parallel-sided.
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Slender Vervain Verbena rigida
Introduced from South America as a garden ornamental. Just a single record from Suffolk, but garden escapes could occur again in urban areas or on waste ground. Unlikely to persist or become established. Flowers July to September. A low-growing bushy species with larger flowers than other vervains on this page. Leaves broad-based with out-turned, marginal teeth.
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Large-bracted Vervain Verbena bracteata
Introduced from South America as a garden ornamental. Just a single record from Suffolk, but garden escapes could occur again in urban areas or on waste ground. Unlikely to persist or become established. Flowers July to September. A low-growing, almost creeping species with large flower bracts, the bracts becoming very apparent as the flower spikes gradually elongate during the flowering season. Leaves relatively short, oval in outline with irregular teeth.
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Hybrid Verbena Glandularia x hybrida
Introduced from South America as a garden ornamental. A very popular garden plant in bedding schemes and hanging baskets but rarely seems to escape into urban areas and never persists for long. Flowers July to September. A low-growing, garden hybrid produced in a variety of colours from deep purple through red and pink to white.
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Frogfruit Phyla nodiflora
Introduced from the Americas as a garden ornamental but not often grown and currently there is only a single record of this species in the wild in Cambridgeshire. Flowers July to September. A low, mat-forming plant that can be a pernicious weed in lawns in the tropics. Not hardy in our climate so unlikely to become established but may turn up in urban environments as a garden throw-out. Flowers may be cream, plae pink or pale lilac.
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