Eutrochium purpureum


Eutrochium purpureum, commonly known as sweet Joe Pye weed, sweet-scented Joe Pye weed or purple Joe Pye weed, is an herbaceous perennial plant in the family Asteraceae. It is native to eastern and central North America, from Ontario east to New Hampshire and south as far as Florida, Louisiana, and Oklahoma.

Description

Eutrochium purpureum is a clump-forming herb that grows to tall and about wide. Plants are found in full sun to part shade in mesic to wet soils. Stems are upright, thick, round, and purple, with whorls of leaves at each node. As the plant begins to bloom the stems often bend downward under the weight of the flowers. The leaves grow to long and have a somewhat wrinkled texture. The purplish flowers are produced in large loose, convex shaped compound corymbiform arrays. Plants bloom mid to late summer and attract much activity from insects that feed on the nectar produced by the flowers.

Taxonomy

Eutrochium purpureum shows a high amount of variability, and up to two or three varieties are currently recognized by current botanical authorities. They differ based in leaf shape, leaf pubescence, and achene glandularity. The precise delineation of these varieties is difficult due to integration between them. The commonly recognized varieties are:
  • Eutrochium purpureum var. carolinianum – Southeastern Piedmont
  • Eutrochium purpureum var. holzingeriMidwestern U.S.
  • Eutrochium purpureum var. purpureum – Widespread in eastern North America
This species hybridizes readily with other species of Eutrochium and where this species and those species overlap in distribution the resulting plants can be difficult to resolve to a specific taxon.

Ecology

Many species of butterflies, moths, bees, and flies visit the flowers.
It is larval host to the eupatorium borer moth, the red [groundling moth], the ruby tiger moth, and the three-lined flower moth.
The larvae of Calycomyza flavinotum, a leaf miner fly, create blotch-shaped mines on the leaves.

Cultivation

Like other Joe Pye weed species, Eutrochium purpureum is cultivated as an ornamental landscape plant, and has escaped from cultivation in parts of New Zealand. E. purpureum and E. maculatum are sometimes confused with each other or treated interchangeably in the gardening world due to their similar appearance.