Diana's Tree (Latin: Arbor Diana or Dianae), also known as the Philosopher's Tree (Arbor Philosophorum), is a dendritic amalgam of crystallized silver, obtained from mercury in a solution of silver nitrate; so-called by the alchemists, among whom "Diana" stood for silver. The arborescence of this amalgam, which even included fruit-like forms on its branches, led pre-modern chemical philosophers to theorize the existence of life in the kingdom of minerals.
In Shadow of Night, Diana and her friend create an Arbor Dianae. When Diana added a few drops of her own blood, the tree began to bear fruit.