Packera is a genus of roughly 75–77 accepted species of flowering plants in the daisy family (Asteraceae), tribe Senecioneae. Members are commonly known as ragworts or groundsels — collective common names shared with their closest relatives — and are sometimes called "American groundsels and ragworts" to distinguish them from Old World Senecio species. The genus was formally described by Á. Löve and D. Löve in 1976, in the journal Botaniska Notiser.
For most of botanical history, Packera species were lumped within the large, heterogeneous genus Senecio, where they were informally grouped as "aureoid senecios." Their recognition as a distinct genus followed evidence from chromosome numbers, a suite of morphological characters, and molecular phylogenetic studies that together supported their separation from the broader Senecio aggregate.
Packera plants are perennial or annual herbs bearing alternate leaves and composite flower heads. The heads typically display bright yellow ray and disc florets arranged on branching stems, giving many species a cheerful, meadow-flower appearance. The type species, Packera aurea (golden ragwort), is among the best-known members and is representative of the genus's floral character.
The genus is predominantly a North American taxon, ranging from Alaska and Canada south through the continental United States, with extensions into parts of eastern Europe, the Russian Far East, Siberia, and Mongolia. A handful of species are also naturalized in parts of Europe such as Germany. Four species are well established in New England: Packera aurea, Packera obovata, Packera paupercula, and Packera schweinitziana.
Distribution
Packera is primarily a North American genus, with native species distributed from Alaska and Canada south through the continental United States. POWO defines the native range as "E. Europe to Russian Far East and Mongolia, N. America," indicating extensions into parts of eastern Europe, Siberia, and Mongolia — likely reflecting species such as Packera cymbalaria that span the Beringian connection. At least one introduction into Germany is documented. In the northeastern United States, four species are recorded from New England: Packera aurea, Packera obovata, Packera paupercula, and Packera schweinitziana.
Ecology
Packera species are members of the aster family and occur across a wide range of habitats in North America. New England populations have been documented in regional flora surveys, indicating tolerance of temperate woodland and meadow conditions. The genus's broad latitudinal range — from Arctic-adjacent regions in Alaska to warm-temperate parts of the United States — suggests ecological diversity across species, with individual taxa adapted to moist woods, streambanks, prairies, and disturbed ground.
Taxonomy
Packera Á.Löve & D.Löve was established in 1976 (Botaniska Notiser 128: 520). Prior to its recognition, all member species were treated within the vastly larger genus Senecio (family Asteraceae, tribe Senecioneae), where they formed an informal grouping of "aureoid senecios." The reclassification was driven by a convergence of evidence: distinctive chromosome numbers, several morphological characters not found across broader Senecio, and molecular phylogenetic data that resolved these taxa as a natural group separate from Old World senecios.
The type species is Packera aurea. POWO (Kew) recognizes 77 accepted species, including one confirmed hybrid, Packera × memmingeri. GBIF records 120 described descendants (including infraspecific entities), reflecting the broader scope of that database. The genus sits within Asteraceae, subfamily Asteroideae, tribe Senecioneae, and is accepted by the Species 2000 & ITIS Catalogue of Life. Taxonomic treatments by Barkley (1962) and Trock (2006) are key references for species-level identification.
