St. Andrew's cross is a small shrub with smooth, reddish bark that peels away in thin strips or flakes.
Flowers are bright lemon yellow; the 4 petals form an oblique cross; there are 4 sepals, of which 2 are large and 2 extremely small; with many stamens. Blooms July–October.
Leaves are opposite, sessile, lighter green below, narrowed at the base, to 1 inch long.
Fruits are ovoid capsules, widest at or below the middle, tapered to a short beak, flattened, with numerous seeds.
Of the two varieties in the state, the more common, var. multicaule, grows only to about 1 foot tall; it is bushy and branches at the base. Var. hypericoides is taller and doesn’t branch at the base, though it branches well above ground level.
Similar species: Missouri has 14 species of Hypericum. All have opposite, simple, entire leaves with small resin dots, flowers with 4 or 5 yellow petals, 4 or 5 sepals, many stamens, and 1 pistil. Many are small shrubs, with twigs often angled or 2-winged. The capsules have numerous seeds.
Height: from 4 inches to 2 feet; sometimes nearly 5 feet tall.
Scattered south of the Missouri River.
Habitat and Conservation
Bottomland forests, rich to dry upland forests, banks of streams and rivers, occasionally margins of ponds and lakes; also roadsides and open, disturbed areas, usually on acidic or sandy substrates. Because the flowers are not abundant or very showy, this species is often overlooked.
This native plant can be used as a wildflower in rock gardens, though it is not winter hardy in northern Missouri. The name comes from the flower shape. According to legend, St. Andrew the Apostle was crucified on an X-shaped cross. This shape, called a saltire, is used repeatedly in European heraldry, flags, and signs.
Deer browse the foliage, and a variety of insects visit the flowers.