Order VIII. Aroideae, Endl.
Floral envelopes absent; or, if present, imperfect, squamiform, sometimes more or less glumaceous.
Araceae and Orontiaceae, Lindl.
Characters.—Flowers generally unisexual, rarely hermaphrodite, arranged upon a spadix, in the axil of a spathe. Perianth either none, or, in the hermaphrodite flowers, rudimentary and scaly. Stamens numerous, or definite and opposite to the segments of the perianth: anthers opening outwards. Ovaries free, 1-, 3-, or many-celled. Fruit succulent or dry, indehiscent. Seeds usually with fleshy or mealy albumen, rarely with none. Usually herbaceous plants with either subterranean tubers (cormi) or a creeping rhizome.
Properties—The fresh plants of this order are frequently remarkable for acridity, which especially resides in the tubers and rhizomes, and often renders them violent poisons. This is especially remarkable in Dieffenbachia Seguina, or the Dumb Cane, a native of the West India Islands, two drachms of whose juice have been known to prove fatal in two hours. The acrid principle (which, perhaps, may be a sulphurated volatile oil) is in many cases readily dissipated or decomposed and rendered inert by cooking. Even drying seems to injure or destroy it. As it is soluble in water, washing removes it from the starch.
The useful qualities of the order depend on starch and aromatic volatile oil: on the former depend the esculent properties of some species, and on the latter the medicinal properties of some.
Colocasia esculenta (also called Culadium esculentum or Arum esculentum) is used in some parts of the world as food. Its large, fleshy, and farinaceous tubers are called yams in Madeira, from whence they were sent me by Mr. Nobrega. I find that when boiled they form a very agreeable substitute for potatoes.
Colocasia Antiquorum is cultivated in Egypt and other parts of the world for the nutritious matter yielded by the tubers.