Jeffersonia diphylla aka Rheumatism Root

Jeffersonia diphylla, or twinleaf, belongs to the barberry family. This perennial herb grows from underground rhizomes. Its native range runs from southeastern Canada into the United States. It occurs in the north-central and eastern states. Wild plants grow in rich, moist woods, often over limestone. They also grow in woods near rivers. North Carolina lists twinleaf as a threatened species. That state status does not establish its global risk.

Twinleaf forms a small, rounded clump and sheds its leaves. RHS gives a garden height of 0.3–1.6 feet [0.1–0.5 metres]. Its spread falls within the same range. NC State reports plants reaching 3 feet [0.91 metres]. The green leaves rise from the base on long stalks. Each leaf splits into two broad lobes, like paired wings. The leaves have smooth edges and no hairs. They measure 0.25–0.5 feet [0.08–0.15 metres] long and wide.

White flowers rise alone on stalks with no leaves. Each flower has eight petals and lasts only briefly. Four sepals fall away early as the flower opens. The blooms measure about 0.08 feet [0.025 metres] across. They open while the new leaves are still small. Bloom dates vary among the sources and their settings. NC State gives March to May; Chicago gives May to June. RHS places flowering in early spring. Bees visit the flowers for pollen. Yellow pods hold brown seeds, with fruit appearing in May.

Grow twinleaf in partial shade or full shade. It needs moist soil that drains well and contains humus. RHS lists clay and loam as suitable soil types. It accepts acid, neutral, and alkaline soils, though lime-rich soil is preferred. Add leaf mould or other humus-rich material in autumn. Avoid needless disturbance, since transplants can take two years to settle. Sow ripe seed or divide established clumps in autumn. Plants raised this way may flower after two to three years. Chicago lists USDA zones 5–7; RHS gives hardiness H6.

Twinleaf suits woodland beds, native gardens, and shaded rock gardens. Groups can make ground cover beneath trees or shrubs. It needs no pruning and has few serious disease problems. Slugs and snails can damage it. PFAF records no known food uses or hazards. It reports past medicinal use for urinary and digestive complaints. It also notes that large root doses can cause vomiting. These records do not establish that eating the plant is safe.