Arum, a genus of monocotyledonous herbaceous perennials, giving its name to an important order. They have starchy cornis or rhizomes, smooth, radical, sagittate leaves with netted veins and an inflorescence consisting of an unbranched monoecious spadix in a sheathing spathe. The spadix bears one-chambered ovaries, anthers with porous dehiscence and rudimentary ovaries, none of these flowers having any perianth, and terminates in a naked club-shaped appendix. The temperature within the unopened spathe rises considerably. Like most of the order, the genus is acridly poisonous. The common British species (A. maculatum) is termed Cuckoo-pint, or Lords-and-ladies.