Erysimum capitatum aka Sanddune Wallflower

Erysimum capitatum is known as western or coastal wallflower. It belongs to the cabbage family, Brassicaceae. Its native range runs from Alaska south to Mexico. It grows across much of western North America. Its range also reaches several central and eastern states. In Missouri, it grows on rocky ground, limestone glades, and bluffs. Elsewhere, its habitats include dry flats and open hillsides. It grows in low valleys and mountain sites.

Garden plants stand about 1–2 feet (0.3–0.61 metres) tall. They spread about 1 foot (0.3 metres) wide. Upright stems bear narrow leaves and rounded flower clusters. Leaves form a rosette at the base and grow along stems. They reach about 0.25 feet (0.08 metres) long. Sources differ on the plant's life span. Missouri Botanical Garden describes its growth and care as biennial. Yet its plant-type entry calls it a herbaceous perennial. Kew lists it as a biennial or small subshrub.

The flowers bloom from May to July. Each flower has four petals. Orange, yellow-orange, and copper tones occur. The flower description also records maroon and near-white forms. Dense clusters make the blooms stand out above the leaves. Long seed pods follow the flowers. These pods have four angles along their length. They reach about 0.33 feet (0.10 metres) long.

Grow this wallflower in full sun or light shade. It suits average soil that drains well. Dry to moderately moist soil meets its needs. It also tolerates drought and shallow, rocky ground. Missouri Botanical Garden lists USDA hardiness zones 3–7. Rock gardens and native plant beds suit its form. It also fits areas where plants can seed themselves. Biennial plants need this seed cycle to persist in gardens. Leave spent flower stems until seed ripens and falls. Or gather ripe seed before cutting the stems back. Spring sowing offers another way to raise plants. Plants For A Future reports germination within about three weeks.

Missouri Botanical Garden reports no major pest or disease concerns. It also rates upkeep as low. Plants For A Future lists no known food uses. It records no known hazards, but this does not establish safety. The same source records traditional medicinal uses of several plant parts. These include skin washes and poultices for wounds or aching joints. Such records describe past use, not proof of safe treatment.