Definition of up a gum tree
: in a very difficult situation that one cannot get out of If they don't deliver the parts we need, we'll really be up a gum tree!
Why is it called gum tree?
Whatever group they're in, gum trees gained their name because they ooze visible amounts of thick, gummy sap if the trunk surface is damaged. Note that sweetgums (Liquidambar spp.) and black gums (Nyssa sylvatica) are not related. Almost all gum trees are native to Australia, where they're the primary food of koalas.
What does by gum mean?
—used to show surprise or determination I looked it up, and by gum, she was right! By gum, I really mean it this time!
