T taigas- swampy forest region of beginning where the tundra ends tannic acid- substance of plant origin used in tanning and dyeing and in making ink and medicine technological- related to the use of science for practical purposes such as the development of machinery thatched- straw covering a roof thrive- to do well, to progress till- to prepare or plow land for growing crops toll- the cost in loss or suffering transitional- changing from stage or place to another triangular- having the form of a triangle tributaries- rivers that flow into a larger river tropical- having to do with or found in the topics, a warm region of the Earth near the equator tundra- treeless, level plain found in artic and subarctic region