tig
is a nice text-mode interface for Git, but it only shows the current branches.
How can I see lost heads and stashes in the tree view?
For tree view it doesn't seem you can't. Manual defines tree view as only working with current revision.
You can switch tree view to refs or stash view though, from tig manual:
4.1. View Switching
Key Action
[..]
r Switch to refs view.
y Switch to stash view.
AFAIK lost heads are only visible through reflog. As for viewing reflog,
It is supported to some extend but probably not well documented. Try:
git reflog --pretty=raw | tig --pretty=raw
(source)