ARUM, a genus of monocotyledonous 'plants of the family Araceae (q.v.), containing 12 species found in Europe and the Mediterranean region, and represented in the British Isles by the well-known lords-and-ladies, cuckoo-pint (q.v.) or wake-robin (A. maculatum), native to Europe and northern Africa. The black calla (A. palaestina), native to Syria and Palestine, is occasionally grown by gardeners. Many plants formerly referred to Arum are now placed under other genera, and numerous plants belonging to other genera are popularly called arums, as the water-arum or wild calla (Calla palustris), cosmopolitan in the northern hemisphere, and the arum-lily, calla-lily or calla of the gardeners (Zantedeschia aethiopica), native to South Africa. (See CALLA ; CUCKOO-PIN T. )