A crystalline tree was an object located on the surface of Delphi Ardu IV and was used by Portal 63 to collect energy from weapons.

One such tree was encountered by an away team from the USS Enterprise-D when they beamed down to the planet and encountered a group of Ferengi who stole a T-9 energy converter. While trying to use their phasers and energy whips to defend themselves, the crystalline tree absorbed the energy from their weapons. (TNG: "The Last Outpost")