Seasonal Wild Flowers

Latin name

Brassica nigra

Family

Brassicaceae

Flowering season

May to September

English distribution

It is found throughout the country but is less common in

northern areas.

See the BSBI distribution map for Black Mustard

Habitat

Black Mustard, which is growing by rivers and on coastal

cliffs and shingle, is probably native, especially in the

Southwest.

That growing on disturbed and waste ground, by roads,

paths, tracks and round arable fields, is probably an

escape from cultivation.

It used to be grown in the UK for mustard seed, but

this now only occurs in France - for French Mustard. 

Rape is the source of seed for English Mustard.

Description

Black Mustard is a native, annual, tall herb, growing

up to 2m.

Sometimes it is tall and straggly and sometimes bushy

and matted.

Flowers are yellow and up to 16mm across.

There are 6 yellow stamens and a capitate stigma, which

may be indistinctly 2-lobed.

The sepals are half spreading.

Fruit pods are up to 2cm long and appressed to the stem.

They have short stalks and short, slender beaks.

The lower leaves are up to 16cm long, deep green, bristly,

and guitar-shaped with a large terminal lobe.

Middle leaves have a wavy outline.

Upper leaves are lanceolate.

Stems are much branched.