By Larry Hodgson
Question: I did a search on your site regarding the difference between an echinacea and a rudbeckia and couldn’t find anything. I was surprised because it seems like a beginner’s question to me and I’m certainly not the first person to ask. Have you ever covered this subject?
Answer: Actually, you are the first person who ever asked me this question. To be honest, I hadn’t even realized there could be any confusion. From my point of view, they’re clearly different, but then, I’ve been growing them ever since I was a child. To me, echinaceas are echinaceas and rudbeckias are rudbeckias. I’d be no more likely to confuse them than a farmer would confuse a sheep with a goat. It’s only as I pondered over how to answer your question that I realized: gee whiz, they really are very similar!
So, let’s take a look:
What They Have in Common
Although the two plants belong to different genera, Echinacea (10 species) and Rudbeckia (25 species), they’re in the same family, the Asteraceae, and in fact, from the same tribe in the family, so they’re very closely related. All species of both genera are herbaceous (there are no woody species) and most are perennials, generally quite cold hardy. They also come from the same area, being strictly of North American origin. Both form rosettes of basal leaves and bear upright flower stalks of varying heights. The inflorescences are very similar, with a daisylike composite flower head and a conelike center. As a result of this central cone, both are sometimes called coneflowers.
The cone is composed of fertile florets and is surrounded by “petals” (actually, ray flowers) of various colors. The two genera even bloom largely at the same season: most from mid- to late summer into autumn.
As for growing them, gardeners use both as ornamentals in flower beds and also in wildflower meadows and find them easy to grow, most doing best in sunny sites and well-drained soils. They attract pollinators, especially bees and butterflies. Neither is terribly subject to predation from deer or rabbits. And both make great cut flowers.
How They Differ
For a long time, it was easy enough to tell echinaceas from rudbeckias by the color of the ray flowers. Echinaceas as grown in home gardens either had pink or white flowers, while rudbeckias had yellow blooms or yellow overlaid with orange, red or brown. There had always been a wild yellow echinacea (E. paradoxa), but few people grew it.
Then in the early 2000s, new hybrid echinaceas in a wide range of colors—red, orange, yellow, white, pink, green and purple—first appeared on the market. From then on, the “pink/white compared to yellow” distinction no longer held.
However, what about cone color? Many of the rudbeckias have dark cones: brown or nearly black, and so have been called black-eyed or brown-eyed Susans. Echinaceas never have black cones or extremely dark ones and mostly range from orange to green to mahogany brown, often changing as the flowers mature.
Of course, it turns out there are also rudbeckias with green cones, but if so, they’re usually a bright green.
True too, double varieties of both show no cones at all … but the double ones start out with a cone … it only becomes covered with ray flowers over time, so that does leave a window of opportunity for identification.
Close up, touch the cones. This is the real giveaway. The very name Echinacea means “hedgehog” (from the Greek echinos) and the cones are covered in spiky appendages called paleae, so they’re prickly. Rudbeckia cones, though, are never prickly.
So, the best way to tell the two apart is to compare cone color and, for even more certainty, texture.
And Then Came the Echibeckias
Just when some semblance of simple classification seemed possible, a new class of plants came along that threw all logical differences out the window.
For a few years now, hybrids between Echinacea and Rudbeckia, called × Echibeckia, have been available to home gardeners. They’re a cross between, I’d guess (because their parentage is a closely guarded secret), the short-lived species Rudbeckia hirta, which they resemble enormously, coming in the same yellow, orange and red shades, with the same near-black cone, and who knows which Echinacea. They’re like a more reliably perennial Rudbeckia hirta, really, and are hard to tell from that plant. They’re sterile and can’t be multiplied by seed.
You still can generally tell echinaceas from rudbeckias by the spikier, non-black cones of the former and dark, smoother cones of the latter. But you’d be hard-pressed to tell an echibeckia from a rudbeckia.