Araceae

The Araceae are a family of monocotyledonous flowering plants in which flowers are borne on a type of inflorescence called a spadix. The spadix is usually accompanied by, and sometimes partially enclosed in, a spathe (or leaf-like bract). Also known as the arum family, members are often colloquially known as aroids. This family of 140 genera and about 4,075 known species is most diverse in the New World tropics, although also distributed in the Old World tropics and northern temperate regions. Many species display very decorative leaves and flowers, and they are widely used for gardening; popular as indoor plants and also outdoor plants where climates are mild, and winter freezes will not generally occur. However, some temperate species are also very popular in Mediterranean-climate gardening, or in moderately cool temperate zones, such as Zantedeschia. Species within Araceae are often rhizomatous or tuberous, and the leaves nearly always contain calcium oxalate crystals or raphides, in varying degrees. The leaves can vary considerably from species to species. The inflorescence is composed of a spadix, which is almost always surrounded by a modified leaf called a spathe. In monoecious aroids (possessing separate male and female flowers, but with both flowers present on one plant), the spadix is usually organized with female flowers towards the bottom, and male flowers towards the top. In aroids with perfect flowers, the stigma is no longer receptive when the pollen is released, thus preventing self-fertilization. Some species are dioecious. Many plants in this family are thermogenic (heat-producing). Their flowers can reach up to 45 °C even when the surrounding air temperature is much lower. One reason for this unusually high temperature is to attract insects (usually beetles) to pollinate the plant, rewarding the beetles with heat energy. Another reason is to prevent tissue damage in cold regions.