Off One's Tree Meaning

Example : 1989, Robert McLiam Wilson, Ripley Bogle, Arcade Publishing (1998), ISBN 1559704241, page 192:  Deirdre was increasingly off her tree in the last sad days of our relationship. Her demands and quirks were ever more extravagant and dislocated.1994, Tom Wells, The War Within: America's Battle Over Vietnam, iUniverse (2005), ISBN 9780595343966, page 391:  "These guys were off their tree," David Hawk recalled. At one point, a VMC activist asked the Weathermen what they were really after. "To kill all rich people," Ayers replied.2010, Anouchka Grose, Why Do Fools Fall in Love: A Realist's Guide to Romance, Tin House Books (2011), ISBN 9781935639008, page 92:  But after her wedding he goes completely off his tree, runs off into the wilderness and starts ranting in verse and writing poems in the sand with a stick.For more examples of usage of this term, see Citations:off one's tree.