The Thyine tree Tetraclinis articulata is also called “thuja” or “thuya,” and, confusingly, “citron” or “citrus” in different parts of the world. Similar to the well-known arborvitae, the thyine is found mainly in the Mediterranean area and across North Africa (Morocco, Algeria). It is a coniferous tree related to cypresses, pines, and cedars. Its identification in the book of Revelation is based on the Greek spelling, thuinos. In some places it is called the sandarac tree on the basis of the clear varnish (sandarac) that is made from the resin. The Romans, who used the wood for cabinet work, called it “citrus” for some strange reason, though apart from the yellow fruit, it bears no resemblance to true citrus trees.

The thyine can reach a height of 9 meters (30 feet). It has scaly leaves like cedars and cypresses, reddish brown bark, and sweet-smelling wood that is resistant to insects.

Source: Each According to its Kind: Plants and Trees in the Bible (UBS Helps for Translators)