Previously included in Cassia and still often sold as such, these species have been reclassified as Senna—a move not accepted by all botanists. Grown for their lavish show of bright yellow, five-petaled flowers that look something like those of potentilla. Blossoms are followed by seedpods that may create litter; to reduce pod production, prune lightly after flowering. Rangy, rank growers should also be cut back periodically to encourage more compact growth. Good for screens, massing, background plantings. Prefer well-drained soil.
Native to Australia. Grows 3 to 5 ft. tall and wide, with attractive, light, airy structure. Gray leaves divided into six to eight needle-like, 1-in.-long leaflets. Bears 3/4-in. bright yellow flowers in clusters of five to eight in winter and spring, with bloom often continuing into summer. In the desert, plants may rest in summer, then resume flowering in fall. Heavy seed production. Very drought tolerant but looks better with moderate to regular water.
FromCalifornia. Erect or sprawlingto 2–3 ft. high and 3 ft. wide.Ovate green leaves to 13/4 in.long. Purple, 1-in. flowers inlate winter, spring. Superiorforms include ‘Mountain Pride’and ‘Salmon Creek’. Little orno water.Senna splendida
From Brazil. Open growth reaches 9 to 12 ft. tall, 6 to 10 ft. wide; habit varies from fairly upright to horizontal. Bright green leaves have four elliptical to oblong leaflets to 3 in. long. Loose clusters of 1/2-in. flowers appear at branch ends from autumn into winter. Heavy seed production.
Hybrid between O. majorana and O. vulgare. Grows to 1–2 ft. tall and wide, wit...
Native toeastern Asia. Grows to 3–8 ft.tall, 10 ft. wide. Leaves 6–12 in.long; flower plumes to 1 ft. ...
Small genus of plants from sunny, moist areas in South America. Species include a spreading mound and ...