Rustwood Trees

Rustwood trees evolved on Mars after many centuries of terraforming.  This tree was used for buildings, slow-burning fuel, and absorbed the rust in the soil making the tree a source of metals as well as wood.  The trees could grow as tall and wide as redwoods from the earth.  Their thick bark is a rusty color giving it its name and is caused by the metals that it absorbed on Mars. 
This tree was so effective in growing, producing oxygen, and absorbing metals and minerals that are normally harmful to other plants that the Green Mage Society have let them grow wild on various Seeded planets which were very useful when the planets were colonized allowing for sturdy building materials for the colonist.  Depending on the planet and the location the color of their bark will be different from their Mars ancestors.  But the name stayed the same with the local added to them for categorizing purposes and to help know what possible metals and minerals it has. 
Various animals and fungi evolved to be able to eat the Rustwood which helped with producing food in the form of mushrooms and made it easier to get the metals and minerals from them. One insect that eats the Rustwood did become the bane to all life around them and it has been the only real negative effect they caused.  It is still unknown how such a creature evolved compared to other creatures that evolved to consume them.
Rustwood has also been used for artworks and ritual tools for various religious groups after being introduced to other Alien races that took a liking to the tree.  One such race that is still in the stone age of their world views it as a Holy Tree of Life.  Torragons have used them for gathering minerals that are important for their race that they have trouble getting from some planets.  This put the Green Mage Society in very good standing with the Torragon people and the Trorragon Merchant Consortium when they gifted seeds of the trees to them after their first encounters with each other.