Stylophorum diphyllum aka Celandine Poppy

Stylophorum diphyllum has two common names: celandine poppy and wood poppy. It belongs to the poppy family. This plant lives for years and has soft, nonwoody growth. It is native to southern Ontario and parts of central and eastern America. It grows in damp woods, near streams, and in ravines. In Missouri, it grows in central and southeastern areas. It also grows beyond its native range in North Carolina.

The plant forms upright clumps. It spreads through seeds and rhizomes, which are underground stems. Growth is slow, though seedlings can extend a patch. Garden plants reach about 1–1.5 feet [0.30–0.46 metres] tall. They spread about 0.75–1 foot [0.23–0.30 metres] wide. The blue-green leaves have deep lobes. Their lower sides have a silver sheen. Most plants have leaves at the base. They also bear two stem leaves that face each other. Fine hairs cover the leaf stalks and lower leaf surfaces. The green stems may have purple bases and fine hairs. Their yellow-orange sap can stain skin.

Yellow flowers open from April to June. In some years, they start in March. Each flower has four petals and may show orange tones. Flowers sit alone or in small groups above the leaves. Their cups measure about 0.13–0.17 feet [0.04–0.05 metres] across. Bees visit the blooms. Cutting off spent flowers can help the plant bloom more. Hairy, blue-green seed pods then form below the leaves. Each hanging pod has four chambers that hold dark seeds. Ants carry the seeds, drawn by their oily attached parts. Chipmunks and mice also eat the seeds.

Grow wood poppy in partial shade or full shade. It needs soil rich in humus that stays moist. It accepts clay, loam, or sand with good drainage. Acidic to neutral soil suits it. It also grows on sites that become wet. Once plants take root, they can stand some drought. But dry soil makes them go dormant in summer. Sources place it in USDA zones 4–9. Chicago Botanic Garden gives a narrower range of zones 4–8. Grow more plants from seed or by dividing clumps.

Use it beneath trees or in shaded wildflower gardens. It also suits rain gardens and sites near ponds. Plants that sow themselves help it settle into woodland plantings. You may need to remove them to keep border edges fixed. The plant does not spread with force. Seedlings take little effort to pull out. Slugs may cause minor harm. Serious pest and disease problems are rare. In some wild sites, garlic mustard threatens its habitat. Native Americans used the sap to make yellow dye.