Seasonal Wild Flowers

Latin name

Verbena bonariensis

Other names

Purple Top

Family

Verbenaceae

Flowering season

July to November

English distribution

It is scattered throughout the country.

For a map see the Botanical Society of Britain and Ireland –

Argentinian Vervain

Habitat

It is a neophyte introduced from South America and grown

in the UK as a garden plant. It has escaped and become

a naturalised on waste ground, tips, cracks in pavements

and walls and as a weed in gardens.

It is on the increase and is classed as an invasive alien in

several countries.

Description

Argentinian Vervain is a perennial, erect, branched herb

growing up to 2m.

Flowers are in short spikes forming mainly terminal

clusters.

Individual flowers comprise a tube up to 7mm long

and a corolla of 5 unequal lobes, 2 slightly smaller than

the other 3.

The corolla is blue to lilac to purple and up to 3.5mm.

There are 4 stamens inside the tube - 2 above and 

2 different below. They have yellow anthers and white

filaments. 

The stile and capitate stigma is at the base of the tube.

Fruits are 4 nutlets.

The 5 sepals are fused into a tube with 5 lanceolate

teeth.

Leaves are slender, lanceolate, serrate and sessile.

Stems are wiry, square and branched.