They are one of my favorite summer flowers, a close clone to the more popular, and well-behaved Black-Eyed Susans, both north American native wildflowers. Both are also excellent pollinator plants, providing food and nectar for a variety of pollinators including native and honey bees.
How to tell the difference. Well, Brown-Eyed Susans are a smaller version of the Black-Eyed Susans. Take a look at the difference:
They look very similar, don’t they.
Black-Eyed Susans are members of the sunflower family. The “black eye” is named for the dark, brown-purple centers of its daisy-like flower heads.
The plants can grow to more than 3 feet tall with leaves of 6 inches. The stalks are usually over 8 inches long with flower diameters of 2 to 3 inches.
Butterflies, bees, and a variety of insects are attracted to the flowers for the nectar. As they drink the nectar, they move pollen from one plant to another, causing it to grow fruits and seeds that can move about easily with the wind.
These plants bloom from June to October. Note that they can be territorial in that they tend to squash out other flowers growing near them.
Black-Eyed Susans are good for cut flowers; they also work well for borders or in containers.
Brown-eyed Susan (Rudbeckia triloba) is the country cousin of the common garden perennial black-eyed Susan (Rudbeckia fulgida).
This native wildflower is distinguished from more cultivated Rudbeckia species not only by its slightly lighter center, or "eye," but by its greater height, its three-lobed leaves, and its tendency to be a less reliable short-lived perennial or biennial. Suitable for gardens in U.S. Department of Agriculture plant hardiness zones 3 through 10, brown-eyed Susan can be coaxed into returning as a perennial with proper care.
Brown-Eyed Susans are often self-pollinated, but it nonetheless attracts numerous nectar-seeking and pollen-seeking insects to its flowers. These visitors include bumblebees, little carpenter bees (Ceratina spp.), digger bees (Melissodes spp.), cuckoo bees (Triepeolus spp., Coelioxys spp.), leaf-cutting bees (Megachile spp.), Andrenid bees (Andrena spp., Heterosarus spp.), and Halictid bees (including green metallic bees).
One of these bees, Andrena rudbeckiae, is a specialist pollinator (oligolege) of Rudbeckia and Ratibida coneflowers.
Other floral visitors include Sphecid wasps, Vespid wasps, Syrphid flies, bee flies, thick-headed flies, Tachinid flies, small to medium-sized butterflies, and the common Chauliognathus pennsylvanicus (Goldenrod Soldier Beetle).
Since it takes them one year to establish and a second year before they bloom, it’s easy to forget where seeds have been scattered. Allowing the plant to bloom and go to seed, though, it the easiest way to allow these North American wildflowers to reseed.
They prefer partly shady areas and mulch over their roots to keep them hydrated.
The foliage is sometimes browsed by deer, rabbits, groundhogs, and other mammalian herbivores.
I have Black-Eyed Susans planted close to my house and brown-Eyed Susans planted in the shady flower beds towards my property line. The smaller Susans make the property seem deeper because they are mistaken for the larger Black-Eyed Susans.
Just think of it as a version of a gardener’s joke.