Cryptotaenia japonica aka Japanese Cryptotaenia

Cryptotaenia japonica is an edible herb in the Apiaceae family. Gardeners call it Japanese parsley or mitsuba. Its native range runs from Vietnam to Sakhalin and eastern Asia. It grows in woods, mountain sites, and damp ditches. Mitsuba refers to the three leaflets that make up its leaves. People grow it for food and for shaded garden beds.

This perennial forms clumps, though growers also raise it as an annual. Garden clumps reach about 1–1.5 feet [0.30–0.46 metres] tall and wide. Flower stems can bring the height to 2 feet [0.61 metres]. NC State reports flower stalks exceeding 3 feet [0.91 metres]. Thick roots support leaves on long stalks from the base. The green leaves have toothed, egg-shaped leaflets and no hairs. Leaves near the flowers may lack the three-part form. Shade gives the plant a more upright shape. Sun can make its growth spread closer to the ground.

Small, star-shaped white flowers grow in loose umbels above the leaves. Missouri Botanical Garden gives the bloom season as June to July. Seeds mature from August to September. After flowering and seed set, the original rosette may die. New rosettes can grow from the same root base. These can form roots of their own and sustain the clump. Gardeners can raise new plants from seed or divide established clumps.

Grow it in moist soil with good drainage and partial shade. It also accepts deep shade and several soil types. Rich, damp soil suits it well. Full sun can scorch or yellow the leaves. It can also make their taste more bitter. Sources place its hardiness within USDA zones 4–8 or 5–8. It needs little upkeep and grows at a moderate pace. Use it in herb beds, containers, borders, or woodland gardens. It may seed freely and form colonies. Removing spent flower stems helps limit unwanted seedlings.

Leaves and stems serve as salad greens or cooked herbs. Roots are edible raw or cooked; seeds provide seasoning. The flowers are also edible. Brief cooking helps retain the leaves' flavour. Large amounts can be toxic, despite its use as food. Repeated skin contact can cause severe irritation. People allergic to related herbs should take care. Slugs and snails may damage plants. Whiteflies and gray mold can cause trouble under glass.