Does it really matter if they cross?

They're lots of advice on saving seed  by isolating plants or seed heads but I can't find much about what happens if you ignore this and let nature take its course.

For example, last year I sowed a lot of old radish seeds together, just to give them a chance. Lots grew and they're flowering. There'll be red ones and white ones, round ones and long ones, summer and winter ones............but, in my view, all radishes taste the same. I don't think I've sown any F1 radish so any seed that is produced will be random radish. Does this matter? I don't think so. 
What about other veg? Beetroot are mostly red although there are yellow, white and stripey ones. I don't like white or stripey beetroot and only grow red or yellow ones. Maybe I'd end up with orange ones. Nice.

I leave kale and other brassicas to flower and, undoubtedly, they've crossed - but, if I only want a plant that provides green leaves for a meal does it matter? 

If anyone knows of information on the "risks" of letting same species plants cross pollinate, please point me to it. I really need to know whether a cross-pollinated seed is likely to produce something inedible, toxic, not worth the effort........

For things you’re just going to be sowing & eating yourself. It’s not an issue at all. As long as the cross pollination doesn’t do something weird to make them inedible in some way. But you won’t know that until it’s too late.
I think the main reason people “professional” get twitchy about crossing is the seeds getting passed around and weakening the varieties. More technical than that, I’m not the person to explain it. You know it all anyway.
You’re definitely right. It’s pretty impossible to find any information on what happens if you let nature do it’s thing. All you can find is the really silly misconceptions about crossing of cucurbits & capsicum.
Maybe that’s you’re next mission in the garden. Write a detailed report about what happened   .

I don't think it makes a deal of difference with leaf and root crops. It's the fruiters and seeders where your cross may end up producing smaller and or less tasty fruits and seeds. Of course with fruits and seeds it may go the other way and the crosses may produce a spectacular size and flavour, in which case you can name them after yourself and make a fortune breeding and selling them

This is a question that's never occurred to me. My seed saving exploits have only come about since meeting the G&G group so I lack experience and very little had the chance to go to seed in my garden. The veges that were over had to be dug up to make room for the next lot. Logically, the variety crosses have been going on for eons, and if anyone was harmed by the resulting cross do you think we'd hear about it? I agree with SC, you're definitely elected to experiment (as you're doing) and tell the world.

It's only squashes that I worry about really, in that sense. They can cross and create toxic new versions of themselves that actually could do you harm, but they'd taste awful, so you'd soon know.
https://www.simplemost.com/toxic-squash-...C%20either.

Would things like radishes all eventually cross back to be more like the original wild form of the plant, the way aqualegia all become blue again? And feral cats allegedly become tabby?

Truth is - I don't really like radishes -that's why I had so many old seeds - so they're probably not the best thing for me to test. The flowers are nice en masse though.
I have been growing all sorts of onions & leeks together including Welsh onions, chives, bunching onions like Ishikura and garlic as edging around a bed. I leave them to flower and self seed. Haven't really noticed any changes and the turnover rate with alliums is much slower than radishes

I guess it depends what you want to gain from your saved seeds. If you're trying to maintain an heirloom variety then I'd want to avoid possibility of crossing.
If you're after food for the table and you're not too concerned re provenance I don't see the worry with crossing. Worst case scenario if you don't like the offspring plants you bin em all and buy some new seeds of a known variety.

Truth is - I don't really like radishes

Have you tried eating the seed pods? I enjoy them much more than the radishes themselves. And roasted radishes are a complete surprise!!

Yes, I have, Sarriss. I graze on them as I admire the flowers. They're in my random seed bed.