Western Coneflower—A Noxious Species?

Abstract

In laboratory tests, dilute foliar extracts of western coneflower (Rudbeckia occidentalis Nutt.) inhibit germination and seedling growth of seeded grasses as do those of some supposedly innocuous species. Under natural conditions on aspen range, measurements of plants of mountain brome growing in close association with coneflower gave doubtful evidence of suppressed growth. Large doses of dried aerial parts of coneflower force-fed to sheep produced no evidence of toxicity or other distress. We found no evidence of coneflower posing any special threat on mountain range, except as a relatively unpalatable increaser species.