Grieve (2005) states that,\" E. cannabinum root-stock is woody and from it rises the erect round stems, growing from 60cms to 1.5m (2 to 5 feet) high with short branches springing from the axils of the leaves, which are placed on it in pairs. The stems are reddish in colour, covered with downy hair and are woody below. They have a pleasant aromatic smell when cut. The root-leaves are on long stalks, but the stem-leaves have only very short rootstalks. They are divided to their base into three, more rarely five, lance-shaped toothed lobes, the middle lobe much larger than the others, the general form of the leaf being similar to that of the hemp (hence both the English name and the Latin specific name, derived from cannabis, hemp). In small plants the leaves are sometimes undivided. They have a bitter taste, and their pungent smell is reminiscent of an umbelliferous rather than of a composite plant. All the leaves bear distinct, short hairs, and are sparingly sprinkled with small inconspicuous, resinous dots. The plant blooms in late summer and autumn, the flower heads being arranged in crowded masses of a dull lilac colour at the top of the stem or branches. Each little composite head consists of about five or six florets. The corolla has five short teeth; though generally light purple or reddish lilac, it sometimes may be nearly white; it is covered with scattered resinous points. The anthers of the stamens are brown, and the very long style is white. The crown of hairs, or pappus, on the angled fruit is of a dirty white colour.\"

Clarkson et al. (2003) state that, \"Branch leaves are simple ovate or lanceolate and all leaves are opposite. The leaves are divided at the base into three, or more rarely five, lance-shaped toothed lobes with the middle lobe being much larger than the others (Grieve, 2003). This gives the leaf the general form of Hemp, hence the name derived from cannabis. Leaves have short hairs and many glands (Clapham et al. 1987) and there are many reported medicinal uses (Glick, 2002; Grieve, 2003). The flowers, which bloom in late summer and autumn, are in heads in dense terminal corymbs, each head with 5-6 small flowers, purple to white in colour (Clapham et al. 1987). Pollination in its native country takes place via Lepidoptera and some flies and bees (Clapham et al. 1987).\"

Plants For A Future Database (2000) states that, \"Eupatorium cannabinum is noted for attracting wildlife.\"

Sharma et al. (1998) state that, \"Extracts of Eeupatorium cannabinum have been used for spleen, liver and biliary diseases, diarrhoea, snakebites, ulcers, wound healing, fever, as a diuretic, anthelmintic and as a repellent against poisonous animals (Woerdenbag, 1993; Madaus, 1938). Extracts of leaves and roots have choleretic, laxative and appetising actions (Woerdenbag, 1993; Hoppe, 1975; Woerdenbag et al. 1991). Aqueous extracts of E. cannabinum had choleretic and hepatoprotective activity in mice against carbon tetrachlorideinduced hepatotoxicity (Lexa et al. 1989, 1990). The aerial parts of E. cannabinum are used as immunostimulating agents in cases of influenza infection, as a remedy against obstipation, for decreasing the level of cholesterol and as a diuretic (Roeder, 1995). The plant is currently used as an ingredient in immunostimulatory drugs (Siebertz et al. 1989). Due to its content of alkaloids, the plant should only be used under professional supervision.\"

Plants For A Future Database (2000) reports that, \"the leaves and flowering tops are alterative, cholagogue, depurative, diuretic, emetic, expectorant, febrifuge, purgative and tonic. The plant has a long history of use as a gentle laxative that does not provoke irritation, though excessive doses cause purging and vomiting. A tea made from the dried leaves will give prompt relief if taken at the onset of influenza. Recent research has shown that the plant might have anti-tumour activity, though the plant also contains pyrrolizidine alkaloids that can cause damage or cancer to the liver. The plant is harvested in the summer and dried for later use. The roots are diaphoretic, laxative and tonic. They are harvested in the autumn and dried for later use. Recently the plant has been found of use as an immune system stimulant, helping to maintain resistance to acute viral and other infections. A homeopathic remedy is made from the leaves. It is used in the treatment of influenza and feverish chills and also for disorders of the liver, spleen and gall bladder. The leaves have been laid on bread in order to prevent it from becoming moldy. The leaf juice has been rubbed onto the coats of animals as an insect repellent.\"

Clarkson et al. (2003) state that, \"E. cannabinum is a typical plant of marshes and fens, also growing on stream banks and in moist woods (Clapham et al. 1987). Soil preferences are nitrogen rich, moist to wet environments, ....\" Heenan et al. (1999) state that, \"E. cannabinum occurs along stream banks, in damp seepages, and in swamps.\" Grieve (2005) adds that, \"This species can be found at the base of cliffs on the seashore, and in other damp places.\"

Plants For A Future Database (2000) states that, \"The scented flowers of E. cannabinum are hermaphrodite (have both male and female organs) and are pollinated by bees, flies, beetles and Lepidoptera (moths & butterflies). The plant is self-fertile.\" Clarkson et al. (2003) report that E. cannabinum produces thousands of tiny wind dispersed seeds. If these seeds are viable because there are suitable pollinators then seed dispersal will lead to range expansion.

Eupatorium cannabinum has the potential to out compete and crowd out native species. It is also able to alter soil nutrients and hydrology potentially reducing the suitability of the area to native flora. This species will form monotypic stands reducing local diversity (Clarkson et al. 2003).

Clarkson et al. (2003) performed a removal experiment in which they removed 116 individual E. cannabinum clumps from a 30x20 metre plot. Thirteen months later E. cannabinum was still not present on the plot. The results of this study have led the authors to conclude that manual removal may be a viable option and state that, \"If enough volunteers can be found, this may a viable control option on a larger scale.\"