LEMNACES. 717 
Starch is usually associated with the acrid principle, and when 
extracted, may be used for food like other starches. The under- 
ground stems or corms of many species, when cooked, are eaten 
in different parts of the world. Some are aromatic stimulants ; 
others expectorant, antispasmodic, or diaphoretic. 
Acorus Calamus, Sweet Flag.—The rhizome is an aromatic stimulant, 
and is regarded by many as a valuable medicine in agues, and as a useful 
adjunet to other stimulants and bitter tonics, It is official in the United 
States and German Pharmacopeeias. It is reputed to be sometimes employed 
by the rectifiers of gin. The candied rhizomes are employed by the Turks 
as a preventive against contagion. In India the rhizome is occasionally 
used as an insectifuge and insecticide, more especially in relation to fleas. 
The volatile oil which may be obtained from it by distillation is employed 
for scenting snuff, and in the preparation of aromatic vinegar. 
Arisema atrorubens, Dragon Root, Indian Turnip.—From the corm of 
this plant a nutritious fecula is obtained in the United States. The corm 
is also given internally as a stimulant, in rheumatism, and in bronchial 
and other affections, and is likewise used extensively as an application to 
aphthous affections in children. 
Arum.—The underground stems or corms of some of the species of this 
genus contain a large quantity of starch: thus those of A. maculatum, Wake- 
Robin, Cuckoo-pint, or Lords and Ladies, a common native of this country, 
are the source of what has been called Portland Sago or Arrowroot; a 
peck of corms yielding about 3 lbs. of starch. But the preparation of this 
starch is now, in a commercial point of view, given up. Formerly the 
corms were also used medicinally as diuretics and expectorants. When 
fresh, they act as an irritant poison.—A. campanulatum and A. indicum 
produce edible corms. 
Caladium bicolor.—The corms of this and other species, when cooked, are 
edible. They are sometimes, but improperly, called ‘ Yams’ in tropical 
countries. (See Dioscorea.) 
Calla palustris has acrid rhizomes, but by drying, washing, grinding, 
and baking, these have been made into a kind of bread in Lapland. 
Colocasia.—C. esculenta and other species have large fleshy corms which 
are much used in the West Indies, Madeira, &c., as food, under the names 
of Yams (see Caladium bicolor), Cocoes, or Kddoes.—C. himalensis has also 
edible corms. They are used for food in the Himalayas.—C. antiquorum is 
applied to a like purpose in Egypt, and the corms of C. macrorhiza are also 
eaten in the South Sea Islands under the name of Tara. 
Dracontium.—The fresh roots of D. polyphyllum are in repute in Malabar 
for their antispasmodic properties. 
Rhaphidophora vitiensis, which is probably a variety of R. pertusa, is 
said by Holmes to be the botanical source of the fibrous portion of the 
remedy now known under the name of ‘Tonga,’ which is used as a remedy 
in neuralgia. Its native name is ‘Nai Yalu,’ or ‘ Walu.’ A. W. Gerrard 
has found this portion to contain a volatile alkaloid, which he has named 
tongine. The other constituent of Tonga is said to be the inner bark of 
Premna tuitensis. (See Premna.) 
Symplocarpus fetidus, Skunk Cabbage.—The root has a very foetid 
odour, especially when fresh. It is considered in the United States as an 
efficacious nervine stimulant, and has been used in spasmodic asthma, whoop- 
ing-cough, catarrh in old people, and in other diseases. Its properties are 
much impaired by keeping. 
Order 4. LmmMNace, the Duckweed Order.—Character.— 
Floating aquatic plants (fig. 252), with lenticular or lobed leaves 
or fronds. Flowers 2 or 3, enclosed in a spathe (fig. 1084), 
