Western natives related to and much resembling evening primrose (Oenothera), with bright yellow, four-petaled flowers over a long summer bloom period. Plants are 1–2 ft. tall. In Zone 13, flowering declines in summer heat, and plants flower in spring and from late summer to fall. Plants spread by rhizomes and are useful for summer color in difficult climates. Shear just before spring growth begins. Plant in well-drained soil. They tolerate regular water if drainage is superb.Calylophus drummondianus
Grows to 1 1/2 ft. high, 2 ft. wide, with narrow, tooth-edged, somewhat drooping leaves and inch-wide flowers. This species blooms for a longer period than C. hartwegii in spring, but it does not rebloom as well in fall.
Native to Iran, Afghanistan, and central Asia. Absolutely covered with slender, sinuous spikes of...
This perennial species can reach 10 ft. tall and 4 ft. wide; it has light green, deeply lobed leaves t...
Native to Siberia. Sturdy, upright habit to 2–3 ft. high and 1 1/2–2 ft. wide. Dark green,...