Parasenecio is a genus of flowering plants in the family Asteraceae (order Asterales), placed within the tribe Senecioneae and subtribe Tussilagininae. The genus was established by W. W. Smith and J. Small in 1922, with Parasenecio forrestii as the type species, based on specimens from the mountains of southwestern China.
The genus comprises approximately 57 accepted species and infraspecific taxa according to GBIF, making it one of the larger genera within Senecioneae. Species are perennial herbs, typically found in montane and subalpine habitats across East and Central Asia. The genus is closely allied with Adenostyles and other members of the subtribe Tussilagininae, and shares characteristic features of the tribe: alternate leaves, discoid (rayless) flower heads, and tubular florets.
The vast majority of Parasenecio species are native to Asia, with centres of diversity in China (including Yunnan, Sichuan, and Gansu provinces), Japan, and Korea. A single outlying species, P. auriculatus, extends the genus's range to the Aleutian Islands in Alaska, representing a disjunct occurrence in western North America.
The generic circumscription of Parasenecio has been revised several times. A 2017 molecular study by Ren and colleagues, published in the Botanical Journal of the Linnean Society, recircumscribed the genus based on nuclear ribosomal and plastid DNA sequences, resulting in the description of two new segregate genera. The name Koyamacalia H.Rob. & Brettell (1973) is treated as a heterotypic synonym.
Etymology
Parasenecio was described by W. W. Smith and J. Small in 1922 in the Transactions and Proceedings of the Botanical Society of Edinburgh (28: 93). The name combines the Greek prefix para- ("beside" or "near") with Senecio, the large related genus in the same tribe Senecioneae, indicating the genus's close affinity to Senecio. The type species is Parasenecio forrestii.
Distribution
Parasenecio is predominantly an Asian genus, with the greatest species diversity concentrated in the mountains of southwestern and central China (Yunnan, Sichuan, Gansu, Anhui, and adjacent provinces), extending through Japan and Korea. One species, P. auriculatus, occurs as a disjunct population in the Aleutian Islands of Alaska, representing the only New World member of the genus.
Taxonomy Notes
The genus was recircumscribed in a 2017 molecular phylogenetic study (Ren, Hong, Wang & Yang-Qing-E., Botanical Journal of the Linnean Society 184(4): 418–443) using nuclear ribosomal and plastid DNA sequences; this work resulted in the description of two new segregate genera and redrew the limits of Parasenecio. The name Koyamacalia H.Rob. & Brettell (Phytologia 27: 270, 1973) is a heterotypic synonym. Within Asteraceae, Parasenecio belongs to tribe Senecioneae, subtribe Tussilagininae, subfamily Asteroideae.
