black-eyed Susan

Rudbeckia hirta is an upright annual (sometimes biennial or perennial) growing 30–100 cm (12–39 in) tall by 30–45 cm (12–18 in) wide. It has alternate, mostly basal leaves 10–18 cm long, covered by coarse hair, with stout branching stems and daisy-like, composite flower heads appearing in late summer and early autumn. In the species, the flowers are up to 10 cm (4 in) in diameter, with yellow ray florets circling conspicuous brown or black, dome-shaped cone of many small disc florets. However, extensive breeding has produced a range of sizes and colours, including oranges, reds and browns.

It is native to eastern and central North America, and is naturalized in the west, being found in all 10 Canadian Provinces and all 48 states of the contiguous United States. It is also naturalized in China.

Butterflies are attracted to Rudbeckia hirta. It is a larval host to the bordered patch, gorgone checkerspot, and silvery checkerspot species. Dragonflies, voracious eaters of mosquitoes, are attracted by the tiny pollinators of these flowers. Rudbeckia hirta is insect pollinated and is recorded to have been visited in northern Florida by Halictus poeyi/ligatus and Megachile petulans.

The plant is thought to be a Native American medicine for various ailments. The roots, though not the seedheads, can be used much like the related Echinacea purpurea with unsubstantiated claims to boost immunity and fight colds, flu and infections. The Ojibwa people used it as a poultice for snake bites and to make an infusion for treating colds and worms in children.

Rudbeckia hirta is widely cultivated in parks and gardens, for summer bedding schemes, borders, containers, wildflower gardens, prairie-style plantings and cut flowers. Numerous cultivars have been developed, of which 'Indian Summer' and 'Toto' have gained the Royal Horticultural Society's Award of Garden Merit. Other popular cultivars include 'Double Gold' and 'Marmalade'. Gloriosa daisies are tetraploid cultivars having much larger flower heads than the wild species, often doubled or with contrasting markings on the ray florets. They were first bred by Alfred Blakeslee of Smith College by applying colchicine to R. hirta seeds; Blakeslee's stock was further developed by W. Atlee Burpee and introduced to commerce at the 1957 Philadelphia Flower Show. Gloriosa daisies are generally treated as annuals or short-lived perennials and are typically grown from seed, though there are some named cultivars.

The specific epithet hirta is Latin for "hairy", and refers to the trichomes occurring on leaves and stems. Other common names for this plant include: brown-eyed Susan, brown betty, gloriosa daisy, golden Jerusalem, English bull's eye, poor-land daisy, yellow daisy, and yellow ox-eye daisy.