Black Mustard
(Brassica nigra)

Description: Flowers have four petals arranged in a cross-shape. Tolerates poor soils, and colonizes fields and disturbed sites. Introduced from Europe.

Habitat: Widespread, especially open areas.

Height: 1 m

Flowering: June

Celandine
(Chelidonium majus)

Description: An introduction from Europe which thrives here in damp sites on the edges of woodland. The hairy stem is brittle and exudes an orange sap if broken.

Habitat: Grows on damp ground, banks, hedgerows and by walls.

Height: 50 cm

Flowering: May - August

Common St. John's Wort
(Hypericum perforatum)

Description: Erect plant with small, narrow leaves. Flowers yellow, 5 thin petals widely spaced in a star-like arrangement. Look closely for the black dots on edges of petals. Introduced from Europe. Native species are less common.

Habitat: Open, sunny habitats, especially woodland edges, abandoned fields.

Height: 80 cm

Flowering: July - August

Common Tansy
(Tanacetum vulgare)

Description:

Habitat: Roadsides.

Height: 1 m

Flowering: July - September