AROIDEAE (Arum family), a large and wide-spread botanical order of Monocotyledons containing about 1000 species in 105 genera. It is generally distributed in temperate and tropical regions, but especially developed in warm countries. The common British representative of the order, _Arum maculatum_ (cuckoo-pint, lords and ladies, or wake robin), gives a meagre idea of its development. The plants are generally herbaceous, often, however, reaching a gigantic size, but are sometimes shrubby, as in _Pothos_, a genus of shrubby climbing plants, chiefly Malayan. _Monstera_ is a tropical American genus of climbing shrubs, with large often much-perforated leaves; the fruiting spikes of a Mexican species, _M. deliciosa_, are eaten. The roots of the climbing species are of interest in their adaptation to the mode of life of the plant. For instance, some species of _Philodendron_ have a growth like that of ivy, with feeding roots penetrating the soil and clasping roots which fix the plant to its support. In other species of the genus the seed germinates on a branch, and the seedling produces clasping roots, and roots which grow downwards hanging like stout cords, and ultimately reaching the ground. The leaves, which show great variety in size and form, are generally broad and net-veined, but in sweet-flag (_Acorus Calamus_) are long and narrow with parallel veins. In _Arum_ the blade is simple, as also in the so-called arum-lily (_Richardia_), a South African species common in Britain as a greenhouse plant, and in _Caladium_, a tropical South American genus, and _Alocasia_ (tropical Asia), species of which are favourite warm-greenhouse plants on account of their variegated leaves. In other genera the leaves are much divided and sometimes very large; those of _Dracontium_ (tropical America) may be 15 ft. high, with a long stem-like stalk and a much-branched spreading blade. The East Indian genus _Amorphophallus_ has a similar habit. A good series of tropical aroids is to be seen in the aroid house at Kew. The so-called water cabbage (_Pistia Stratiotes_) is a floating plant widely distributed in the tropics, and consisting of rosettes of broadish leaves several inches across and a tuft of roots hanging in the water. [Illustration: _Arum maculatum_, Cuckoo-pint. 1. Leaves and inflorescence. 2. Underground root-stock. 3. Lower part of spathe cut open. 4. Spike of fruits. Showing in succession (from below) female flowers, male flowers, and sterile flowers forming a ring of hairs borne on the spadix.]