Arum italicum aka Italian Arum

Arum italicum, or Italian arum, belongs to the arum family. This woodland perennial grows from swollen underground storage organs. Its native range spans Europe, North Africa, and the Middle East. It also occurs naturally on islands in the eastern Atlantic. Wild plants grow near streams, among hedges, and beside old walls. Some grow on stony ground near the sea. It has spread beyond its native range into other countries.

Garden plants reach 1–1.5 feet [0.30–0.46 metres] tall and wide. RHS gives an upper size of about 1.6 feet [0.5 metres]. The plant forms clumps as its underground organs multiply. Its glossy, arrow-shaped leaves have pale veins across green blades. Leaves can reach 1 foot [0.30 metres] long. New leaves appear in fall and last through mild winters. Cold weather can kill them, with fresh leaves returning in spring. The foliage dies back in summer as the plant rests.

Flowers appear in April and May. Tiny flowers grow on a slender central spike called a spadix. A pale, hood-shaped spathe wraps around this spike. The spathe may have purple edges. The flowers give off an odor that attracts small flies. These flies carry pollen between flowers. After flowering, the leaves and spathe fade. Clusters of berries then stand above the bare ground. They change from green to orange-red and can last through August.

Italian arum prefers moist soil rich in humus, with good drainage. It grows in partial or full shade, though sources also list sun. It accepts a broad range of soil types and pH levels. USDA guidance places it in zones 5–9. Plants need a sheltered site in colder parts of zone 5. RHS rates its hardiness as H6. Gardeners use it in woodland beds, shaded borders, and containers. Its leaves and fruit provide interest in different seasons. It needs no pruning and has few serious pests or diseases.

Its rapid spread can outweigh its garden value. Seeds and underground organs help it colonize new ground. It is invasive in parts of the western and mid-Atlantic United States. Removal is difficult, and surviving underground parts can regrow. All parts are poisonous, and sap can irritate skin and eyes. Eating it can swell the tongue and throat and impair breathing. It is also toxic to pets. PFAF records food uses for thoroughly processed tubers, including starch extraction. This historical use does not make the raw plant safe to eat.