These hardy and frost tender perennials and shrubs are found in North and South America, Europe and Asia and are grown mainly for their flowers, though some are valued for their ornamental foliage. The name commemorates Mithridates Eupator, King of Pontus, who is credited with discovering that one of the varieties could be used as a remedy for poison. Eupatorium purpureum (Joe Pye Weed) is a vigorous growing perennial that can reach a height of 7 feet. Its coarse, finely toothed, mid-green leaves are finely serrated and lance-shaped to oval. They are produced in whorls along purple stems. The tiny, pinkish-purple flowers are borne in thick terminal heads, from late summer to fall; they are a great attraction for butterflies. Eupatorium coelestinum (Mist-flower / Hardy Ageratum) is a hardy perennial that produces light blue flowers in the fall. Eupatorium ligustrinum is a Mexican shrub that grows from 8 to 12 feet high. It is a tender perennial that is often grown as a winter-blooming plant for the greenhouse, but can be grown outdoors in mild climates. This large bush produces white or white tinted with purple flowers in the spring and summer.

These plants should be planted in moist, fertile, humus-rich soil, in a sunny or partially shaded position. When they are grown indoors, they should be planted in three parts fibrous loam, one part leaf mold and dry cow manure, and one part sand. When tender, indoor kinds have finished flowering, they should be pruned back and kept cooler and a bit drier for a few weeks. They may then be propagated or repotted and started into growth again. They all need a lot of water while they are growing actively.

The herbaceous kinds are easily increased in the spring or fall by dividing the clumps or by removing shoots, a few inches long, in the spring and inserting them in a frame. All the shrubby kinds can be reproduced by cuttings placed under glass in the spring. As soon as they have formed roots, they should be moved into larger pots. When the final pots are filled up with roots, they should be given manure water regularly. Seeds may also be sown in the spring.

These are the hardy kinds that are suitable for the herbaceous border, wild garden, or the edge of a pond or stream -
 
Eupatorium aromaticum;
Eupatorium perfoliatum (Common Boneset);
Eupatorium coelestinum (Mist-Flower / Hardy Ageratum);
 Eupatorium rugosum (White Snakeroot)
Eupatorium purpureum (Joe Pye Weed).
 
These are the kinds for the greenhouse -
 
Eupatorium ligustrinum (often called Eupatorium micranthum);
Eupatorium riparium;
Eupatorium atrorubens;
Eupatorium sordidum (Eupatorium ianthinum) (must be grown in a greenhouse having a minimum temperature of 50 degrees or outside in the far South);
Eupatorium macrophyllum.