Black-Eyed Susan

In the 1970s, researchers explored the different patterns of reflected ultraviolet light in the corollas of this and other rudbeckias. Although UV light is invisible to humans, bees and some other insects can see it. The UV patterns in the flowerheads are especially attractive to the appropriate pollinators.

Genus Rudbeckia is native to the United States and Canada, but members of the genus have been introduced to Europe because of their popularity as garden flowers. There are about 25–30 species in this genus.

Nine Rudbeckia species have been recorded growing wild in Missouri; in the following list, the most commonly encountered species are at the top, with the rarer ones at the bottom:

• Brown-eyed Susan (Rudbeckia triloba): to 5 feet tall; much-branched, with many small flowerheads only 1 inch across; leaves with coarse teeth; blooms June–November; low, wet woods, roadsides, edges of woods, streamsides, valleys; statewide except the Bootheel lowlands.
• Wild goldenglow, or tall or cutleaf coneflower (Rudbeckia laciniata): to 9 feet tall; rank-growing, usually unbranched; flowerhead with green disk and only 6–10 yellow rays; leaves with long leaf stems, 3–7 deeply cut lobes, and a variety of teeth and lobes, to 10 inches long and 6 inches wide; upper leaves much smaller, often 3-lobed, with or without teeth; blooms July–September; covers large areas in bottomlands, also valleys near streams, and other low, moist areas; statewide except Bootheel lowlands.
• Missouri black-eyed Susan (Rudbeckia missouriensis): like black-eyed Susan (R. hirta) but usually smaller, very hairy, and with all but the lowest leaves linear (grasslike); lowest leaves lance-shaped; blooms June–October; mainly in limestone and dolomite glades and other dry, rocky places in the Ozarks and north to the Missouri River.
• Sweet coneflower (Rudbeckia subtomentosa): hairy, branching plant to 6 feet tall; leaves very hairy, with large teeth; lower leaves often 3-lobed; upper leaves ovate; flowerheads large, about 2 inches across, with 12–20 yellow rays; disk brown to purplish brown, half-domed; blooms July–October; grows in moist places near streams, prairies, roadsides; occurs statewide.
• Orange coneflower (Rudbeckia fulgida): like Missouri black-eyed Susan (R. missouriensis), but with broader leaves, and the basal leaves with leaf stems (not sessile); scattered in moist habitats in the southern half of Missouri, excluding the Bootheel.
• Clasping coneflower (Rudbeckia amplexicaulis): all leaves unlobed, untoothed, glabrous (hairless, smooth to the touch); all but the lowest leaves are stalkless and heart-shaped, clasping; upland prairies and glades; natively, uncommon in Jasper and Newton counties; introduced elsewhere, especially in western Missouri.
• Rough coneflower (Rudbeckia grandiflora): ray florets 1¼–2 inches long, usually drooping; disk egg-shaped to conical, ½–1¼ inches long; usually in open, disturbed areas; uncommon and sporadic, possibly introduced to Missouri from nearby states; a native population may exist in Phelps County.
• Great coneflower, or cabbage coneflower (Rudbeckia maxima): foliage grayish, hairless; flowerheads large, at the tips of long stalks, the disk lengthening from conical to cylindrical with age, the yellow ray florets drooping; grows in nearby states and has been collected in Missouri along a railroad in Jackson County; sometimes cultivated in gardens.