Very funny, watched a low-quality VHS during a trip to Lincoln and didn’t take notes. Much has happened since then, so rather than try to scrape my memory for details, here’s a capsule summary by J. Rosenbaum:

Walter Matthau, cast wildly against type, plays a spoiled playboy suddenly deprived of his wealth who plots to marry and murder a wealthy, klutzy, and dysfunctional botanist (May, playing sort of a female Jerry Lewis). May’s savage take on her characters irresistibly recalls Stroheim; she’s at once tender and corrosive (as well as narcissistic and self-hating). This is painful comedy, to be sure, but there’s a lot of soul and spirit behind it.

and more, from Essential Cinema. Sorry to overquote.

The movie – adapted from Jack Ritchie’s story “The Green Heart” — ends with a last-minute turnaround in which the husband saves his wife from drowning on a camping trip and decides with a certain resignation that he’s actually growing fond of her. But May’s script showed Matthau’s character committing at least two other murders prior to this showdown, poisoning both a blackmailer and his bride’s crooked lawyer (Jack Weston). These scenes were cut by the studio, and May attempted to sue Paramount to block the release of their re-edited version.