TEAK, one of the most valuable of known timbers. The Sanskrit name of teak is saka, and it is certain that in India teak has been known and used largely for more than 2,000 years. Teak is a large deciduous tree, of the family Verbenaceae, with a tall, straight but often buttressed stem, a spreading crown, and the branchlets four-sided with large quadrangular pith. It is a native of the Indian peninsula, Burma and Siam, and is also found in the Philippine islands, in Java and elsewhere in the Malay archipelago, although there is no record of its being native in these places. In India proper its northern limit is 24° 40' on the west side of the Aravalli hills, and in the centre, near Jhansi, 25° 30' N. lat. In Burma it extends to near Myitkyina, in lat 25° 30'. In Bengal or Assam it is not indigenous, but plantations have been formed in Assam as far as the 27th parallel. In the Punjab it is grown in gardens to the 32nd. Teak thrives best in districts with a mean annual rainfall of more than 5o in. The mean annual temperature which suits it best lies between 75° F and 8i° F. Near the coast the tree is absent, and inland the most valuable forests are on low hills up to 3,00o ft. It grows on a great va riety of soils, but there is one indispensable condition—perfect drainage or a dry subsoil. On level ground, with deep alluvial soil, teak does not always form regularly shaped stems, prob ably because the subsoil drainage is imperfect.
During the dry season the tree is leafless; in hot localities the leaves fall in January, but in moist places the tree remains green till March. At the end of the dry season, when the first monsoon rains fall, the fresh foliage comes out. The leaves, which stand opposite, or only whorled in very young specimens, are from 1 to 2 ft. in length and from 6 to 12 in. in breadth. On coppice shoots the leaves are much larger, and not rarely from 2 to 3 ft. long. In shape they somewhat resemble those of the tobacco plant, but their substance is hard and the surface rough. The small white flowers are very numerous, on large erect cross-branched panicles, which terminate the branches.
The tree seeds freely every year, but its spread by self sown seed is impeded by the forest fires of the dry season, which in India generally occur in March and April, after the seeds have ripened and have partly fallen. Germination is slow.
The bark of the stem is about half an inch thick, grey or brownish grey, the sapwood white; the heartwood of the green tree has a pleasant and strong aromatic fragrance and a beau tiful golden-yellow colour, which on seasoning soon darkens into brown, mottled with darker streaks. The timber retains
its aromatic fragrance to a great age.
Durability of Teak.—The principal value of teak timber for use in warm countries is its extraordinary durability. In India and in Burma beams of the wood in good preservation are often found in buildings several centuries old, and instances are known of teak beams having lasted more than i,000 years. In one of the oldest buildings among the ruins of the old city of Vijayanagar, on the banks of the Tungabhadra in southern India, the superstructure is supported by planks of teakwood II in. thick. These planks were examined in 1881; they were in a good state of preservation and showed the peculiar structure of teak timber in a very marked manner. They had been in the building for 5oo years (Indian Forester, vii. 26o). In the wall of a palace of the Persian kings near Baghdad, which was pillaged in the 7th century, two Ameri cans found in 1811 pieces of Indian teak which were perfectly sound (Ouseley, Travels in Various Countries of the East, ii. 28o, n. 67). In the old cave temples of Salsette and elsewhere in western India pieces of teak have been found in good preserva tion which must have been more than 2,00o years old.
Teak is used for shipbuilding, for furniture, for door and window frames, for the construction of railway carriages, and for many other purposes. White ants eat the sapwood, but rarely attack the heartwood of teak. It is not, however, proof against the borings of the teredo, from whose attacks the teak piles of the wharves in the Rangoon river are protected by metal.
Growth.—In its youth the tree grows with extreme rapidity. Two-year-old seedlings on good soil are 5 to 1 o ft. high, and in stances of more rapid growth are not uncommon. In the plantations which have been made since 1856 in Burma, the teak has on good soil attained an average height of 6o ft. in 15 years, with a girth, breast high, of 19 inches. This is between 16° and 18° N. lat., with a mean annual temperature of 78° F and a rainfall of ioo inches. In the Burma plantations it is estimated that the tree will, under favourable circumstances, attain a diameter of 24 in. (girth 72 in.) at the age of 80. Timber of that size is market able, but the timber of the natural forests which is at present brought to market in Burma has grown much more slowly, the chief reason being the annual forest fires, which harden and impoverish the soil. In the natural forests of Burma and India teak timber with a diameter of 24 in. is never less than ioo and often more tharf 200 years old. The trees are not generally more than zoo to 15o ft. high, even under favourable circumstances.