We have two types of oat growing here: the cultivated variety and the wild variety (Avena sativa and probably Avena fatua). The cultivated oat is a bit of an accident really: we sometimes feed our goats and chicken with oat which then get transfered to the compost, and the compost is used for our veg patch, where we find oat begins to grow!
So, we have wild and cultivated growing side by side, and it’s interesting to see the similarities. According to Wikipedia the cultivated oat is closer related to this wild oat, and not the one in the picture. But still, if you look in the picture you can see how one can become the other, just by selecting the bigger grain you can, over a few thousand years, come up with something completely different! Maybe I should give it a go? lol