Extensive forests of the _játi_, or teak of India[30], are found in almost all the eastern provinces; but the most valuable and important are in the central districts, situated inland, between _Semárang_ and _Sidáyu_, and particularly in the districts of _Blóra_, _Jípang_, and _Padáng'an_.
Of the teak tree there is but one species known, the tectona grandis of Linnæus, the tekka of Van Rheede, and the jatus of Rhumphius. Its natural history has been already fully detailed, and all the kinds generally enumerated are merely varieties. These are usually distinguished among the natives of Java by names derived from the quality and colour of the wood. The principal are the _játi kápur_, the chalky teak, and a kind varying in colour, and on account of its excellence termed _játi súng'gu_, or the true teak. The former is the most common: its wood is of a whitish hue, and it sometimes contains calcareous concretions in nodules or streaks. This sort is chiefly employed for common domestic purposes, and though inferior in quality to many others, from its abundance and comparative cheapness, is perhaps the most generally useful. The _játi súng'gu_ is harder, closer, and more ponderous, and particularly selected for ship-building. The colour of the wood is of different shades, from light to intense brown, with a cast of violet verging sometimes to red or black. If the stem is covered with spines, or rather pointed scales, it is called _játi dúri_, but in its texture and quality it agrees with the _játi súnge'gu_. Besides these the natives distinguish, as _játi gémbol_, those excrescences or protuberances which are produced from a variety of the _játi_, furnishing materials for handsome cabinet-work.
The teak tree on Java grows at a moderate elevation above the level of the ocean. It is generally conceived, that the timber afforded by forests growing on a soil of which the basis is limestone, and the surface uneven, gravelly, or rocky, is the hardest, the freest from chalky concretions, and in all respects the best; but in laying out a teak plantation, a soil consisting in a great proportion of black vegetable mould, is always selected for the purpose of obtaining a rapid growth. The teak tree is slender and erect. It shoots up with considerable vigour and rapidity, but its expansion is slow. Like all other trees affording useful timber of a close grain, it is many years in arriving at maturity. Under favourable circumstances, a growth of from twenty to twenty-five years affords a tree having about twelve inches diameter at the base. It requires at least a century to attain its perfection, but for common purposes, it is usually felled when between thirty and fifty years old[31].