Common Name: Thoroughwort

General Information

Eupatorium perfoliatum is an erect, herbaceous perennial plant producing a clump of stems that can grow 40 - 100cm or more tall[].
A very popular domestic medicine in N. America, where it is commonly harvested from the wild for local use and trade.

Known Hazards

None known

Botanical References

,

Range

Eastern N. America - Quebec to Manitoba, south to Florida and Texas.

Habitat

Moist, low ground, marshes, roadsides, swamps, wet pastures; at elevations up to 500 metres, sometimes higher[]. Wet woods, scrub, fens and damp grassland[]. Sandy soils in Texas[].

Properties

Medicinal Rating
Habit	Perennial
Height	1.20 m
Pollinators	Insects
Self-fertile	Yes
Cultivation Status	Wild

Cultivation Details

Eupatorium perfoliatum is a very cold-hardy plant, able to tolerate temperatures down to about -25°c when fully dormant[].
Succeeds in ordinary well-drained but moisture retentive garden soil in sun or part shade[].
Plants seem to be immune to the predations of rabbits[].
A polymorphic species[].

Edible Uses

None known

Medicinal

Thoroughwort is one of the most popular domestic medicines in North America[, ] where it is used in the treatment of influenza, colds, acute bronchitis, catarrh and skin diseases[]. It has been shown to stimulate resistance to viral and bacterial infections, and reduces fevers by encouraging sweating[]. The plant, however, should be used with some caution since large doses are laxative and emetic and the plant might contain potentially liver-harming pyrrolizidine alkaloids[].

The leaves and flowering stems are antispasmodic, cholagogue, diaphoretic, emetic, febrifuge, laxative, purgative, stimulant, vasodilator[, , , ]. A hot infusion of the dried leaves and flowers is used as a very effective treatment to bring relief to symptoms of the common cold and other similar feverishness - it loosens phlegm and promotes its removal through coughing[, , ]. This herb is practically unequalled in its effectiveness against colds[]. It is also used in the treatment of rheumatic illness, skin conditions and worms[].
The leaves and flowering stems are harvested in the summer before the buds open, and are dried for later use[].

A homeopathic remedy is made from the fresh plant, harvested when it first comes into flower[]. It is used in the treatment of illnesses such as flu and fever[].

Other Uses

None known

Propagation

Seed - sow spring in a cold frame and only just cover the seed. Prick out the seedlings into individual pots when they are large enough to handle and plant them out into their permanent positions in the summer.
Division in spring or autumn[]. Very easy, the clumps can be replanted direct into their permanent positions.