References

For Rudbeckia

Campbell, J.J.N., and W.R. Seymour, Jr. 2013. Towards a revision of the Rudbeckia fulgida complex (Asteraceae), with description of a new species from the blacklands of southern USA. Phytoneuron 2013-91: 1-27. Google Scholar

Cronquist, A. 1980. Asteraceae, Volume I, Vascular flora of the Southeastern United States. University of North Carolina Press, Chapel Hill, N.C. Google Scholar

Kelley, J.M. 2023a. Rudbeckia grandiflora var. alismifolia (Asteraceae) in Oklahoma. Phytologia 105(1): 15-17. Google Scholar

Kelley, J.M. 2024b. Evidence for treating two taxa of Rudbeckia (Asteraceae) as species. Phytoneuron 2024-28: 1-14. Published 8 May 2024. ISSN 2153 733X Google Scholar

Perdue, R.E., Jr. 1957. Synopsis of Rudbeckia subgenus Rudbeckia. Rhodora 59: 293-299. Google Scholar

Urbatsch, L.E., and P.B. Cox. 2006a. Rudbeckia. In Flora of North America Editorial Committee. 2006c. Flora of North America north of Mexico. Volume 21, Magnoliophyta: Asteridae, part 6: Asteraceae, part 3. Oxford Univ. Press, New York, NY. 616 pp. Google Scholar