Rudbeckia fulgida Aiton
Original Published Description:
Rudbeckia fulgida was first described by William Aiton in 1789 in Hortus Kewensis, or, A catalogue of the plants cultivated in the Royal Botanical Garden at Kew. In 1945, Arthur Cronquist recognized four varieties of Rudbeckia including var. sullivantii, var. umbrosa, var. fulgida and var. missourriensis in Volume 47 of Rhodora. Then in 1957, Robert Perdue, Jr., contributed a new scheme to Rhodora excluding var. missourriensis but adding four more varieties including vars. deamii, speciosa, palustris, and spathulata.
Rudbeckia fulgida is considered an endangered species in the state of New Jersey. In the state of Indiana, var. fulgida is considered rare while var. umbrosa is listed as endangered. (USDA, 2010.)
Habitat loss due to development and agriculture is the main threat to this species, but cultivars may also threaten local populations. (Molano-Flores, 2005.)
Key taken from Flora of North America. (Urbatsch & Cox, 2006.)
1. Basal leaf blade lengths ± 3 times widths……….............................15b Rudbeckia fulgida var. fulgida
1. Basal leaf blade lengths to 2 times widths
2. Cauline leaves not notably smaller distally
3. Stems densely villous-hirsute; basal leaf margins mostly coarsely crenate; cauline leaf margins
sharply serrate (teeth remote); Illinois, Indiana, Ohio….........15a Rudbeckia fulgida var. deamii
3. Stems glabrous or sparsely villous-hirsute; basal leaf margins entire or crenate; cauline leaf
margins coarsely serrate to lacerate; ne United States….15e Rudbeckia fulgida var. speciosa
2. Cauline leaves notably smaller distally (except var. umbrosa)
4. Ray laminae 25–40 mm; palea margins eciliate (Indiana, Michigan, Ohio) …...............................
..................................................................................................15f Rudbeckia fulgida var. sullivantii
4. Ray laminae 10–30 mm; palea margins ciliate
5. Leaf bases (basal and proximal cauline) broadly rounded to cordate (Alabama, Arkansas,
Georgia, Indiana, Kentucky, Mississippi, Missouri, North Carolina, Ohio, South Carolina,
Tennessee, Virginia)….................................................... 15g Rudbeckia fulgida var. umbrosa
5. Leaf bases (basal and proximal cauline) usually acute, attenuate, cuneate, or rounded
6. Cauline leaf blades lanceolate to ovate; ray laminae 15–25+ mm; Arkansas, Missouri,
Oklahoma, Texas…......................................................15c Rudbeckia fulgida var. palustris
6. Cauline leaf blades oblanceolate to broadly spatulate or pandurate; ray laminae 10–15
mm; Alabama, Florida, Georgia, North Carolina, South Carolina, Tennessee, Virginia,
West Virginia…........................................................15d Rudbeckia fulgida var. spathulata
"Perennials, to 120 cm (stoloniferous, rosettes forming at stolon apices). Stems glabrous or moderately hirsute (branches spreading). Leaves: blades lanceolate to broadly ovate or elliptic (not lobed), herbaceous, bases attenuate to cordate, margins usually entire or serrate, sometimes lacerate, apices acute, faces glabrous or hirsute to strigose; basal petiolate, 5–30 × 1–8 cm; cauline petiolate, 2–25 × 0.5–7 cm, bases attenuate to cordate or auriculate. Heads borne singly or (2–7) in corymbiform arrays. Phyllaries to 2 cm. Receptacles hemispheric to ovoid; paleae 2.5–4 mm, (apical margins usually ciliate) apices obtuse to acute, abaxial tips usually glabrous. Ray florets 10–15; laminae elliptic to oblanceolate, 15–25 × 3–6 mm, abaxially strigose. Discs 12–16 × 10–18 mm. Disc florets 50–500+; corollas proximally yellowish green, brown-purple distally, 3–4.2 mm; style branches ca. 1.3 mm, apices rounded. Cypselae 2.2–4 mm; pappi coroniform, to 0.2 mm."
Based on a 2009 study, Rudbeckia fulgida var. Sullivantii 'Goldsturm' is a tetraploid with a 1Cx value of 8.9 picograms. (Palmer, Ranney, Lynch & Bir, 2009.)
Ecology and Distribution
Varieties deamii, fulgida, spathulata and umbrosa flower late summer to fall. The remaining varieties, palustris, speciosa and sullivantii may begin flowering earlier in the summer but can also bloom in the fall. (Urbatsch & Cox, 2006.)
The following detailed information regarding var. sullivantii is taken from the Journal of the Torrey Botanical Society, July 2007.
"A Rudbeckia fulgida var. sullivantii head took about a month to bloom starting from when the ray florets uncurled to the final disk floret blooming at the apex. In one week involucral bracts uncurled, followed by ray florets extending and then recurving back on top of the bracts. In this time the receptacle became more conical in shape. The perfect, dark purple-brown disk florets matured acropetally, each taking 4-6 days for the corolla to develop. The purple-brown style pushed the pollen up through the corolla tube displaying the pollen, followed by the style bifurcating. If the yellow-orange pollen was not removed from the style branches (via a pollinator), the pollen remained stuck to the tips of the style branches as they separated. Due to the close proximity of each floret in the head, it was possible for pollen to come into contact with the disk floret of the row below. The glabrous style remained bifurcated and developed stigmatic papillae on the upper surface, suggesting receptivity. The style branches continued to curl until the sweeping hairs at their tips almost touch the underside of the branch. The styles remained this way until any lingering pollen turned white (10-14 days). Following this pollen color change, the style soon shriveled inside the corolla tube. This sequence of events means that florets at the base of the head were senescing while florets at the apex were at anthesis. As the head aged, the tips of the ray florets turned a paler yellow color. These greenhouse flower head phenological observations were also confirmed in the natural populations at MNTP."
Scott, Lynne & Brenda Morano-Flores. The Journal of the Torrey Botanical Society. Vol. 134 No. 3 pp. 362-368. 2007. "Reproductive Ecology of Rudbecia Fulgida Ait. Var. Sullivantii (C. L. Boynt and Beadle) Cronq. (Asteraceae) in Northeastern Illinois."
Rudbeckia fulgida uses a wide array of insects as pollinators. This particular species is very vigorous and has a high natural disease-resistance. For this reason, it is commonly hybridized with a number of other wildflowers in the hopes of creating progeny with the same resistance. Tomanthera auriculata is a known hemiparasite, attaching haustoria to the roots of Rudbeckia fulgida. (Cunningham & Parr, 1990.)
The species range spans from southeastern Canada down the Atlantic Coast to Florida and west to Texas and Oklahoma up through Missourri, but the varieties are localized within.
Var. deamii is found only in Illinois, Indiana and Ohio and var. palustris only grows in Texas, Oklahoma, Arkansa and Missourri. Var. sullivantii is localized to the northeast U.S. Var. spathulata spans from Florida throughout most of the coastal plain. Vars. fulgida and umbrosa also span the coastal plain, with fulgida's range extending north and umbrosa's range extending west. Var. speciosa is found throughout the entire range except Texas, Oklahoma, Indiana, Tennessee, the Carolinas and Florida.
Varieties deamii, palustris, spathulata, sullivantii and umbrosa prefer mesic to wet habitats from stream banks to woodlands, swamps and fens, and they tend to favor shade. Var. speciosa prefers mesic open woods and var. fulgida prefers more dry, open habitats.
Rudbeckia fulgida is considered a short-lived perennial. Some varieties tend to outlast others, and many cultivars only last one season.
Diseases in Rudbeckia fulgida are mostly fungal, including grey mold and powdery mildew. They can develop leaf spots if infected by certain species of Pseudomonas and Xanthomonas, and they are subject to some aphids.
Polysaccharides isolated from the green parts of Rudbeckia fulgida have shown immunomodulatory properties, including adjuvant activity. Cherokee people have used a root extract to treat earaches, swelling and snakebites.
- Rudbeckia speciosa Wender. (synonym)
- Rudbeckia umbrosa C. L. Boynton & Beadle (synonym)