Rudbeckia is a genus of herbaceous plants in the Asteraceae family. Mostly perennial plants, some species are biennial. The flowers are composite heads, made up of a prominent, raised central disc surrounded by yellow, ray-florets. The dark center, set against the bright yellow rays, gives rise to the names “black and brown-eyed susan.” These inflorescences are “cone-shaped” because of their decumbent (downward-pointing) petals, hence their other common name “coneflowers.”

Their common names can be quite confusing. We are often asked, “what is the difference between a black-eyed susan and a brown-eyed susan?” In reality, the names are interchangeable, and are  used for multiple species within the genus. To make things more confusing, many of them are referred to as “coneflowers”. We most often use the name coneflower to describe Echinacea species. And, just to add insult to the confusion, someone decided to call them “orange” coneflowers. But, clearly, they are yellow, not orange.

Species and Range: 

There are about 30 recognized species and all are native to North America. The greatest diversity occurs in the Southeastern and Midwestern United States. They live in a variety of habitats, though they are most common in prairies, grasslands, fallows, meadows, and wetlands.

In Pennsylvania, one can find four different species of Rudbeckia in the wild: 

Rudbeckia fulgida (Orange Coneflower, or Black-eyed Susan)

Two natural variations of this species are found in PA: Rudbeckia fulgida var. fulgida (orange coneflower) and Rudbeckia fulgida var. speciosa (showy black-eyed Susan). These are long-lived, clump forming perennials. Rudbeckia fulgida var. fulgida is our favorite variety of the species, and the one we grow most of. It is a very dependable garden perennial. It generally grows 24 to 30 inches tall x 12 to 24 inches wide. Full sun is best, but very light shade is okay too. It will grow well in average to dry, well-drained, fertile soils. It tolerates drought, road salt, and poor soils. Blooms from mid-summer to late autumn. Oh, and like we said before, despite the name it is not typical-orange…but we will grant it that it has a brilliant, golden-yellow flowers!

Rudbeckia hirta (Black-eyed Susan)

This species is commonly seen in fields, meadows, fallow fields, and even roadside ditches. It is a short-lived species, sometimes only growing as an annual but may live for a few seasons. We generally do not grow this species very often because of its short-lived tendency. But, it is an excellent addition to gardens, meadow plantings, and restoration areas as it can quickly spread by seed and fill blank areas. It grows 24 to 36 inches tall x 12 to 24 inches spread. It prefers full sun but will grow in partial shade. Very adaptable and will grow in almost any soil that is not too wet or heavy. Blooms from mid-summer to autumn and will reseed in favorable conditions.

Rudbeckia laciniata (Cutleaf Coneflower, or Green-headed Coneflower)

A very cool and somewhat unique Rudbeckia among the PA-native species. This species’ central disc is pale yellowish-green (not brown or black). It is also quite tall, growing anywhere from 5 to 7 feet tall and spreading by rhizomes to form colonies. It is a wetland species, found in wet meadows, streambanks, glades, lake margins, and swamps. But, it will grow in any soil that does not become too dry for prolonged periods. It is tolerant of heavy clay soils, flooding, poor soils, and road salt. This plant will grow in full sun or part shade. The flowers begin to emerge in mid-summer and continue to bloom thru late summer.

Rudbeckia triloba (Brown-eyed Susan)

Probably the most widespread species in the state, you can find it almost anywhere. The brown-eyed Susan, as so many call it, is a biennial species. This means it lives for two seasons. The first season it grows a basal rosette of leaves that remain somewhat close to the ground, and the second year it blooms and then dies. The plants produce thousands of seeds and eagerly reseed in favorable conditions. You can grow this plant in almost any soil type from dry to wet, fertile to poor, compact to well-worked…it almost does not matter to this plant as long as it receives plenty of sunshine. Expect this species to grow anywhere from 12 to 60 inches tall x 12 to 48 inches wide. Its size greatly depends on soil quality and moisture. Richer, moister soils will result in larger, bushier plants.

 

Pollinators and Birds:

Rudbeckia are Keystone Species here in the mid-Atlantic region. Keystone species are native plants that provide the maximum ecological benefits to native bees, butterflies, and moths. They not only support the adult and larval forms of our native insects, but in turn those insects support our native bird populations. Did you know that 96% of our songbird species need to feed their nestlings soft-bodied insect larvae? Rudbeckia host over 20 species of moth and butterfly larvae and over 25 species of specialist bees. Specialist bees must feed their larvae the pollen of only certain plant species. Without those plants, the bees cannot thrive or reproduce.

Many songbirds, gamebirds, small mammals, and even some waterfowl will feed on the seeds of Rudbeckia species. American goldfinches are some of the most common birds to forage seed from the heads of Rudbeckia plants.