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Packera glabella
Also called Cress Leaf Groundsel, Cress Leaved Groundsel, Smooth Groundsel, Yellowtop
Packera glabella (formerly Senecio glabellus) is one of several plants with the common name butterweed. P. glabella has also been called cressleaf groundsel and yellowtop. It is native to central and southeastern North America but spreads so aggressively, overtaking other native plants, that it is considered a noxious weed in Ohio (a designation primarily for agriculture), although the Ohio Invasive Plants does not list the plant on its invasive species list. A 2020 blog post by the Ohio Natural Areas & Preserves Association describes butterweed as "a new invasive species" in Ohio's forested wetlands, noting its rapid spread and impact on native plant communities.
The leaves, flowers, and seeds of P. glabella contain toxic compounds called pyrrolizidine alkaloids, which are known to cause liver damage, such as seneciosis, in livestock. Chronic exposure to this compound may lead to loss of appetite, sluggish behavior and in severe cases, aim walking or neurological impairment. These alkaloids act as natural biocides deterring herbivore animals from consuming them. Beyond toxicity to livestock, pyrrolizidine alkaloids can leach into surrounding soil and water during heavy infestations, which may influence soil invertebrate communities and microbial activity.
P. glabella is toxic to humans if ingested, causing liver damage, but documented cases are rare and most concern livestock.
P. glabella is native to the United States, with a native range from Texas to Florida, and from Florida along the coast to Virginia and as west as Nebraska. Records show that the organism was collected in Illinois as early as 1932. The organism thrives in moist, low-lying areas and can bloom in either sun or shade as long as the location remains wet.
Packera actinella · Small's ragwort · Shale barren ragwort · Golden ragwort · San Bernardino ragwort · Bolander's ragwort · Brewer's ragwort · Woolly groundsel · Bittercress ragwort · Beaver Mountain ragwort · Cleveland's ragwort · Widehead groundsel
Text excerpted from the Wikipedia article Packera glabella by its contributors, under CC BY-SA 4.0; the excerpts are shared under the same licence.
Life form, climate and native range: World Checklist of Vascular Plants, Royal Botanic Gardens, Kew (CC BY 3.0), reformatted; see Plants of the World Online.
