Blood thorns are ghastly-looking trees that grow only in the deepest cavern layers. They are distinguished from their peers by being the densest tree in the game (though glumprongs come close), being approximately half as dense as most stones, and by their unique crimson color. When cut down they produce extremely heavy crimson wood that cannot be found anywhere else, making for heavy-set but colorful furniture and slightly less useless wooden ballista bolts. Curiously, trampled young blood thorns are purple rather than dark gray, presumably due to the plant having been "bruised" - this is in imitation of the "blood" in their name.
Among subterranean trees blood thorns are unique in that they can grow in cavern layers that are devoid of water - when this happens, blood thorns will be the only plants present. This means that every so often a fortress may happen to have a large stock of the tree in its caverns. Some dwarves prefer blood thorns for their "sickening appearance."
[NAME:blood thorn][NAME_PLURAL:blood thorn][ADJ:blood thorn]