arum

Arum is a genus of flowering plants in the arum family, Araceae, comprising around 20–30 species of herbaceous perennials with underground rhizomes. They are native to Europe, North Africa, and western Asia, often occupying woodland or damp habitats, and several species have been cultivated as ornamentals and naturalized in parts of North America and elsewhere.

The most distinctive feature of Arum plants is the inflorescence, a spadix surrounded by a spathe that is often hooded and colored green, purple, white, or mottled. The flowers are usually concealed within the tubular spathe. In many species, the spadix emits scents that attract flies; some exhibit thermogenesis, producing heat to volatilize odors and guide pollinators. The leaves typically appear after flowering and can be large and glossy, sometimes with striking patterns in species such as Arum italicum.

Fruits form as a cluster of bright red or orange berries on the spadix after pollination, with birds and mammals dispersing them. All parts of Arum plants contain calcium oxalate crystals and can cause irritation if ingested or if the tissue is chewed, so handling may irritate sensitive skin.

In horticulture, arums are valued for their striking inflorescences and foliage in milder climates. Common species include Arum maculatum (lords-and-ladies) and Arum italicum. Note that arum lilies sold as ornamentals refer to unrelated genera such as Zantedeschia.