I feel like I may be accidentally selecting for hulls on my field peas that are harder to see.
A lot of cultivars of Vigna unguiculata* have hulls that turn purple when they're mature, but before they start to dry out. Purple hull and pink eyed peas are two common varieties like that, and it makes them real easy to spot for harvesting. Other kinds stay green, or maybe just go a little paler/yellower when they're ready, and those you have to hunt for among the leaves.
I don't know what varieties I started out with, but there's at least two normal-sized kinds in the mix, and hull color varies among them both. I never get every pod picked at the optimal time, but the ones I miss dry well on the vine, so I just pick them when I do find them, and put those dried bean in a jar to plant next year. Which means, as far as my unnatural selection, that the ones that don't turn a convenient color when they're ready have an advantage. They're more likely to get 'selected' for propagation (i.e. forgotten & then found later), as long as they produce well enough to be statistically significant in the seed jar.
Beans are pretty stable over the planting generations, as they mostly pollinate themselves, but they do produce crop-outs from time to time (like my exciting new fat variety - I'll do a post about them soon), so the color may drift over time. I've been growing these from my own saved seeds for ~10 years, and at least some of them are still purple (maybe half? maybe less), but then I don't really know what I started with, so idk if they've changed. I could start taking more notes, I guess.
*This species includes all the field peas, cowpeas, black eyed, purple hull, lady peas, Sea Island red peas, and a hundred other cultivars of similar beans. I call all those field peas, as a general term. Yardlong beans are also in this species, and some other Asian varieties I'm not as familiar with. Crowder peas, too.
Now, some people (and google) seem to think that crowder peas and field peas are the same thing, and they're wrong. Similar, yes. Closely related, yes. Cooked about the same, also yes. A crowder pea might even be considered a type of field pea, but not every field pea is a crowder. They crowd together in the pod, see, and it changes the shape of the pea, leaving an indent where the next one pushed up against it.
Proper crowder peas:
vs. ordinary purple hulls:
