Dogs mercury

Appearance

A member of the spurge family , it is a herbaceous, downy perennial with erect stems bearing simple, serrate leaves. The dioecious inflorescences are green, bearing inconspicuous flowers from February to April. It characteristically forms dense, extensive carpets on the floor of woodlands and beneath hedgerows.

Naming

The plant's common name derives from the plant's resemblance to the unrelated ''Chenopodium bonus-henricus'' . Since ''Mercurialis perennis'' is highly poisonous, it was named "dog's" mercury . It has also been known as boggard posy.

Habitat

Besides those three variations of M. perennis there are six habitat forms in nature:
⤷  f. silvatica . Leaves elongated, elliptic-lanceolate, pointed. Mid-nerve and veins of the leaves usually are thicker.
⤷  f. ovatifolia . Leaves ovate to ovate-lanceolate, the upper part of the stem above the middle region generally hangs down. This form grows on sunny slopes in bushes and thickets or on entirely exposed dry situations.
⤷  f. angustifolia . Grows, like the preceding, in sunny situations, but the leaves are comparatively narrow and lanceolate, more hairy and thicker.
⤷  f. robusta . Leaves unusually large, 10–15 cm. long, and over 5 cm. broad. Seeds 4–5 mm. long. Plants very much taller and more robust, sometimes attaining a height of about 60–65 cm. Generally found under old oak or beech in fairly damp and shady localities.
⤷  f. saxicola . Leaves elongate-elliptic, 4-5 times as long as broad, gradually tapering towards the apex. Both the upper and lower faces of the leaves hairier. Generally on exposed chalky hills.
⤷  f. variegata . Its leaves possess beautiful mottled patches of yellow and white, and by continued cultivation, this may be further improved.

Uses

The dog's mercury is poisonous by itself but with a thorough drying/heating, one is able to destroy its poisonous quality. The juice of the plant is emetic, ophthalmic and purgative. It can be used externally to treat menstrual pain, ear, and eye problems, warts, and sores. A lotion can be made from the plant for antiseptic external dressing due to its ability to soften and moisturize the skin.A fine blue dye can be obtained from the leaves although it is able to be turned red by acids and destroyed by alkalis. It is often permanent and colouration is similar to indigo. A yellow dye can be obtained from the leaves. The seeds are also a good source of drying oil.