ARACEAE or AROIDEAE, the arum family, a large group of monocotyledonous plants containing upwards of loo genera and more than i,000 species, of which the cuckoo-pint in Great Britain, and the jack-in-the-pulpit, found in eastern North America, are familiar examples. Neither of these small plants, however, gives more than meagre indication of the char acters of this interesting plant family which attains its most conspicuous development in the Tropics. The aroids are generally herbaceous, often, however, reaching gigantic size ; but they are sometimes shrubby climbing plants. Many are peculiar in form and habit and grotesque in appearance. Various climbing species of Philodendron have feeding roots which penetrate the soil and clasping roots that fix the plant to its support. Some are epi phytes, and a few, such as the water lettuce (Pistia Stratiotes), are floating plants.
The leaves, which show great variety in size and form, are generally broad and net-veined, though sometimes sword-shaped and parallel-veined. In Arum (q.v.) the blade is simple. In other genera the leaves are divided and sometimes very large ; those of Dracontium (tropical America) may be 15 ft. high. In the ceriman (Monstera) the large perforated leaves appear as if cut full of holes. The small flowers are crowded on thick, fleshy spikes, which are usually enveloped by a large leaf (bract), the spathe, which is often the most conspicuous feature of the plant. For example, in the cuckoo-pint the spathe is large and green ; in the jack-in-the-pulpit it is purple-striped ; in the callas it is white or yellow; and in the anthuriums it is scarlet. In Arnorpliophallus, an East Indian genus, the "flower" (spathe and spadix) often exceeds 3 ft. in length. The true flowers are often extremely simple, sometimes, as in Arum, reduced to a single stamen or pistil. The fruit is a berry. Usually the plants contain a poisonous acrid juice. The underground stems (rhizomes or tubers) are rich in starch; those of the tropical taro (q.v.) providing a valuable article of food. From the rhizomes of the cuckoo-pint Portland arrowroot was formerly prepared. The starchy corms of the jack in-the-pulpit were utilized for food by the Indians of eastern North America.
Besides the cuckoo-pint, the Acorns Calamus (q.v.) or sweet flag occurs in Great Britain, though it is supposed to have been introduced. In North America about 15 native species of aroids are found, chiefly in the southern and eastern United States. Among these are the jack-in-the-pulpit, green dragon, golden-club, sweet flag, wild calla, water-lettuce (qq.v.) and skunk-cabbage. Only one native species, the western skunk-cabbage (Lysichiton kamschatensis), occurs on the Pacific coast. Because of their unusual foliage and inflorescence numerous species of Alocasia, Anthurium, Caladium, Calocasid, Die ff enbachia, Scindapsus, Xanthosoma, and other genera are grown in greenhouses for orna ment and as curiosities. A good series of tropical aroids may be seen in the aroid house at Kew.