As my wife ate her porridge this morning she asked "what exactly are oats?" and it turned out to be an interesting question because of Vavilonian mimicry.

https://en.wikipedia.org/wiki/Vavilovian_mimicry

Vavilovian mimicry - Wikipedia

@dpiponi

Huh! I was weeding in the garden at the weekend, and thought "If weeds wanted to survive, they'd evolve to look like the plant they are next to". I had no idea it was a Thing.