Pod colours, and some genetics

There's a surprising amount of variety in the colours of pea pods. We all know the standard green ones, but it's possible to get the following as well:

*Purple (courtesy of the Guardian)


*Yellow (grown by me, years ago)


*Red (courtesy of the lovely Rebsie Fairholm)


*Bluish-green (no picture, sorry, but I am growing a couple of types with this colour so I can show you later in the year)