Osbertia Greene

Osbertia E. L. Greene

A small genus of three perennial species native to the Mexico. The rays are yellow often with some reddish tint on the under (abaxial) side. Osbertia was treated as monotypic Haplopappus sect. Osbertia by Hall (1928). Turner and Sundberg (1986) added a second species, O.chihuahuana. Nesom transferred the third species O. bartlettii into the genus; it was first described as Aplopappus bartlettii S.F. Blake and subsequently treated as Heterotheca bartlettii (S.F. Blake) M.C. Johnston. Turner and Sundberg (1986) thought Osbertia appeared "especially close" to some taxa in Noticastrum in part due to being stoloniferous and having a "graduated pappus" which they described as a "single series" in their generic description. Semple (2006) showed the pappus differed in the three species but consisted of several series in in two of them. urner and Sundberg (1986) also stated that it is "probably as closely related to Noticastrum and Heterotheca as it is to Erigeron." Nesom (1991) included the genus in his subtribe Chrysopsidinae, and subsequently Nesom (2000) placed it close to Chrysopsis. Osbertia has not been included in any DNA sequence study to date. The only chromosome number reports for the genus are several for O.stolonifera with x=5 (2n = 10).

Nesom (2000) recognized three species in the genus:

• Osbertia stolonifera
• Osbertia chihuahuana
• Osbertia bartlettii

Last revised 7 May 2025 by J.C. Semple

© 2025 J.C. Semple, including all photographs unless otherwise indicated