This is a tree that spawns in the nether by the Natura mod.
The tree is very large with a 2x2 trunk stemming more than 8 blocks down, the leaves are a deep red color, the trunk is a blotchy mostly orange color with other shades in there.
The wood provides 4x wooden planks and the tree and anything with the word bloodwood in its name are fire resistant (apart from tools), for example the Bloodwood Door.
The wood also has it's own set of tools: pickaxe, sword, ect.
This tree can be planted in the overworld by placing Tainted Soil (or Netherrack?) high up off the ground and planting on the bottom of the block. Over time the sapling will grow into a full Bloodwood Tree like it would in the Nether.
The tree is found in the nether growing upside-down from the ceiling of the dimension.