The arum family spans the titan arum and the world's smallest flowering plant
One plant family holds both the largest unbranched flower spike on Earth, the titan arum, and the tiniest flowering plant, the duckweed Wolffia. Some members heat their blooms to 45 degrees Celsius to lure beetles, others stink of rotting meat, and almost all are laced with needle-like crystals that sting the mouth.
Araceae, or aroids, carry their flowers on a fleshy spike called a spadix, usually cupped by a leaf-like bract, the spathe. Estimates of their size vary, with one count of 114 genera and about 3,750 species and another accepting 143 genera. They are richest in the American tropics but also grow in Old World tropics and northern temperate lands. Many creep from rhizomes or tubers, climb as vines or perch on trees. Where a plant bears separate male and female flowers, the females usually sit at the bottom of the spike; where flowers are bisexual, the stigma stops being receptive before pollen appears, preventing self-fertilisation.
Heat is a remarkable trick. Eastern skunk cabbage, the titan arum, the elephant-foot yam and the voodoo lily all warm their flowers well above the surrounding air, rewarding beetle pollinators and protecting tissue in cold places. The titan arum and the dead-horse arum lily also reek of carrion to draw flies, and the warmth helps spread the smell.
Nearly every aroid contains raphides, sharp crystals of calcium oxalate. Taro, Xanthosoma and Alocasia leaves can be eaten after cooking, as can ripe Monstera deliciosa fruit, but raw tissue can cause painful burning, swelling and difficulty swallowing that may last up to two weeks. That is why Dieffenbachia is nicknamed dumb-cane, a label that could fit almost any genus in the family.
Gardeners know the family well through Monstera, Philodendron, Anthurium, peace lilies and ZZ plants, while Anubias and Cryptocoryne are prized in aquariums. Theophrastus described aroids in antiquity, but they were only recognised as a group in the 16th century. Heinrich Schott built the first major classification around 1860 from flower features, and Adolf Engler a rival one based on anatomy. Gene studies later showed the duckweeds belong inside the family, a move the 2009 APG III system accepted.
Source: Araceae
