Linnaeus first descriped Rudbeckia laciniata in Species Plantarum in 1753. In 1884, Asa Gray described variety humilis in Synoptical Flora of North America, and var. heterophylla was added by M.L. Fernald and B.G. Schubert in Rhodora in 1948. Shortly thereafter, Cronquist described var. ampla in Vascular Plants of the Northwest, in 1955. Finally, Robert E. Perdue, Jr. added the last variety, var. bipinnata, in an article in Rhodora in 1962. Thus, the five varieties of R. laciniata are ampla, the Rocky Mountain cutleaf coneflower, bipinnata, the Northeastern cutleaf coneflower, humilis, the Southeastern cutleaf coneflower, heterophylla, the Florida coneflower, and laciniata.
Rudbeckia laciniata is listed as a threatened species by the state of Rhode Island. (USDA, 2010.)
Ozone has deleterious effects on R. laciniata. (Chappelka, Neufeld, Davison, Somers and Renfro, 2003.)
Rudbeckia laciniata has been reported as having chromosome numbers of both n=18 and n=19, along with a number of ploidy levels. (Urbatsch, Baldwin & Donoghue, 2000.)
Rudbeckia laciniata has a rapid growth rate and can reach heights over 9 feet.
Although there are no known morphological differences between Ozone-sensitive and insensitive types, the stomatal response is significantly lower in sensitive plants. (Grulke, Neufeld, Davison, Roberts & Chappelka, 2006).
Rudbeckia laciniata plays host to the aphid Uroleucon rudbeckiae. (Service, 1984.) Its nectar and pollen attract a variety of bees, wasps, moths and butterflies. Its leaves are a foodsource for certain caterpillars, but the vegetation may be poisionous to mammalian herbivores. Finches may eat seeds.
Rudbeckia laciniata can be found throughout most of the U.S., excluding the Northwest, and the southern reaches of Canada. Var. ampla grows west of the Great Plains and in British Columbia, and var. laciniata can be found everywhere east of ampla's range. The other varieties have very small, localized distributions. Var. bipinnata grows from Maryland and Pennsylvania up through New England, except for Maine and Vermont. Var. humilis grows from Virginia south to Georgia and west to Alabama and Tennessee, and var. heterophylla grows only in Levy County, Florida. (Urbatsch & Cox, 2006.)
For more information, see the map provided by Flora of North America.
Wet habitats along streams and woods
Vars. ampla, bipinnata, humilis and laciniata begin flowering in the summertime, but var. heterophylla can start to produce flowers in the spring. Flowering of all varieties continues into the fall. (Urbatsch & Cox, 2006.)
Corynespora cassiicola is a pathogen responsible for eye-spots and eventual death of the leaves of R. laciniata. (Da Silva, Soares & Barreto, 2005.)
Although poisoning is unlikely, this plant has caused poison by ingestion in the past, specifically in cattle and swine. As a precaution, it is recommended to suppress its growth in grazing areas.
First and foremost, Rudbeckia laciniata and its cultivars are grown as ornamentals. The leaves of young plants have been harvested and used as greens in salads.