Tree Lorn Acre Slitheen-Blathereen was a member of the Slitheen-Blathereen family and the husband of Leef. Both he and Leef had a poor opinion the Blathereen side of their family, and were addicted to eating Rakweed.
In 2009, Tree and Leef hatched a plan to spread the Rakweed across Earth and gain huge profit, landing their ship in Antarctica and using it as a base. They put their scheme into motion by giving a Rakweed plant as a gift to Sarah Jane Smith, gaining her trust by first foiling a Slitheen plan to destroy Earth and posing as bounty hunters. The Rakweed then started to infect London, including Sarah Jane's son, Luke. Enraged by this, Sarah Jane teleported herself to the ship and threatened him and Leef with a water gun filled with vinegar. Leef tricked Sarah Jane into letting down her guard by feigning ignorance of the Rakweed's effects, and having Tree falsify a removal of the plant. When Sarah Jane lowered her weapon, Leef was able to restrain her. However, Sarah Jane later managed to escape and find a way to destroy the Rakweed and stop the infection. Tree and Leef then transported themselves to Sarah Jane's attic, and tried to kill her and her friends. In retaliation, Sarah Jane had Mr Smith replicate the sound of an alarm bell to destroy the Rakweed in Tree and Leef's stomachs. This caused a massive methane gas build up which killed them both. Clyde Langer referred to this as farting themselves to death. (TV: The Gift)