Asteraceae : Rudbeckia hirta

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Family Name

Asteraceae

Common Name

Black-eyed susan

Description

Rudbeckia hirta is an annual (sometimes biennial or perennial) herb with ascending stem growing 30–100 cm tall. The stems are covered in long, white, stiff, spreading hairs and are generally unbranched or have a few branches in the upper half. The leaves are simple, alternate, petiolate, mostly basal, extremely variable in shape. The lower leaves are oblanceolate, 10–18 cm long and covered by coarse hair. The middle leaves are short petioled, lance-linear and reduced in size. The upper-most leaves are greatly reduced and sessile. The leaf margins are entire o with a few shallow teeth. The inflorescence consist of 1 to a few long-stalked flower heads at the top of the plant and arising from upper leaf axils. The receptacle is up to 2 cm in diameter, hemispheric to ovoid surrounded by hairy, elongated involucral bracts. There are 18-21 yellow to yellow-orange ray flowers with ligules 2-4 cm long, sometimes purplish near their base, surrounding the numerous brown to purplish brown disk flowers. The achenes are four-sided, ~2 mm long and lack a pappus. Black-eyed Susan bloom from May to September, mostly in disturbed prairies, roadsides and waste areas in northeast and southwest South Dakota.

Additional Notes

Black-eyed Susan produce nectar that attracts butterflies, bees and other insects. Their achenes provide food for several songbirds. In a native plant garden, they readily reseed themselves and can be maintained for years.

Horticulture Notes

Seed Collection: Collect seed in mid to late summer.

Germination: Seeds are somewhat dormant. Spring sowing will result in some gemination. Treatment with a 1 mM Ethephon solution for 2 weeks or 30-day cold treatment will greatly improve spring sowing. Fall sowing is also an easy option.

Soils: Tolerates most soil types but prefers well-drained soils.

Light: Full sun

Water: Prefers moist conditions but can withstand dryer conditions.