Plant Profile: Epilobium

Epilobium is a genus belonging to the evening primrose family, encompassing approximately 197 species. Commonly known as willowherbs, these plants are primarily herbaceous, with some being annuals and others perennials, while a few take the form of subshrubs. Willowherbs are known for their rapid growth, often covering extensive areas and potentially becoming the predominant species within their ecosystems.

The Hairy Willowherb, also referred to as Codling-and-Cream, is frequently found in the eastern United States, reaching heights of up to 6 feet. It features hairy leaves and stems, along with notched petals. In contrast, the Rock Fringe is a low-growing variant native to the western United States. Fireweed is known to emerge in areas affected by fire. Annual species are more prevalent in cooler climates but can occasionally appear as cool-season weeds in warmer regions.

While some of these plants are cultivated, they require careful management to prevent uncontrolled spread. Their soil preferences vary by species; some thrive in wet environments, while others favor drier conditions.

It is important to note that willowherbs are increasingly found in container nurseries, likely due to contamination from nursery crops. To mitigate this risk, it is essential to inspect liners to avoid introducing these plants. Additionally, measures should be taken to prevent them from seeding in or near production areas. Current herbicides labeled for use in container nurseries are not very effective against willowherbs, and the rankings for herbicide efficacy are based on limited experimental findings.

Certain species within this genus are classified as invasive or noxious weeds in various states.