170. Diospyros kaki.—The Chinese date plum or persimmon. The fruits vary in size from that of a medium-sized apple to that of a large pear; they also vary much in their flavor and consistency, some being firm, and others having a soft custard-like pulp, very sweet and luscious. The Chinese dry them in the sun and make them into sweetmeats; they are sometimes imported, and in appearance resemble large-sized preserved figs. These plants are being quite largely cultivated in some of the southern States, and the fruit is entering commerce.
171. Dipterix odorata.—This leguminous plant yields the fragrant seed known as Tonka bean, used in scenting snuff and for other purposes of perfumery. The odor resembles that of new-mown hay, and is due to the presence of coumarine. The tree is a native of Cayenne and grows 60 to 80 feet high.
172. Dorstenia contrayerva.—A plant from tropical America, the roots of which are used in medicine under the name of Contrayerva root.
173. Dracæna draco.—The Dragon's Blood tree of Teneriffe. This liliaceous plant attains a great age and enormous size. The resin obtained from this tree has been found in the sepulchral caves of the Cuanches, and hence it is supposed to have been used by them in embalming the dead. Trees of this species, at present in vigorous health, are supposed to be as old as the pyramids of Egypt.
174. Dracænopsis Australis.—Ti or cabbage tree of New Zealand. The whole of this plant is fibrous and has been used for paper making. The juice of the roots and stem contains a small amount of sugar and has been used for producing alcohol.
175. Drimys winteri.—This plant belongs to the magnolia family and furnishes the aromatic tonic known as Winter's bark. It is a native of Chili and the Strait of Magalhaens.
176. Dryobalanops aromatica.—A native of the Island of Sumatra. It furnishes a liquid called camphor oil and a crystalline solid known as Sumatra or Borneo camphor. Camphor oil is obtained from incisions in the tree, and has a fragrant, aromatic odor. It has been used for scenting soap. The solid camphor is found in cracks of the wood, and is obtained by cutting down the tree, dividing it into blocks and small pieces, from the interstices of which the camphor is extracted. It differs from the ordinary camphor in being more brittle and not condensing on the sides of the bottle in which it is kept. It is much esteemed by the Chinese, who attribute many virtues to it. It has been long known and is mentioned by Marco Polo in the thirteenth century.
177. Duboisia hopwoodii.—The leaves of this Australian plant are chewed by the natives of Central Australia, just as the Peruvians and Chilians masticate the leaves of the Erythroxylon coca, to invigorate themselves during their long foot journeys through the country. They are known as Pitury leaves.
178. Durio zibethinus.—A common tree in the Malayan Islands, where its fruit forms a great part of the food of the natives. It is said to have a most delicious flavor combined with a most offensive odor, but when once the repugnance of the peculiar odor is overcome it becomes a general favorite. The unripe fruit is cooked and eaten, and the seeds roasted and used like chestnuts.
179. Elæis guineensis.—The African oil palm is a native of southwestern Africa, but has been introduced into other regions. It grows to a height of 20 to 30 feet and bears dense heads of fruit. The oil is obtained by boiling the fruits in water and skimming off the oil as it rises to the surface. It is used in the manufacture of candles. In Africa it is eaten as butter by the natives.