This subject is often very confusing due to the poorly worded information out there and common misconceptions. You can't look at it as "the banana" and "the plantain", because really there is only "the banana". "Plantian" is a term used to decribe bananas that are usually higher in starch content and often need to be cooked, while what is commonly refered to as "the banana" really should be called "dessert banana", these are the bananas we know and love that are sweet and can be eaten ripe without cooking. There is also cooking bananas which are refered to different then plantains because they need to be cooked while most plantains will turn to a dessert banana if let ripen long enough. So you see, the edible banana group as a whole is divided into these 3 groups, dessert, plantian and cooking. However, there is no clear distinction between any of these, its more of a spectrum with some bananas being full dessert, or half dessert and half plantain, or full plantain or full cooking. You will also often hear about plantain bananas being from M. balbisiana and dessert bananas being from M. acuminata, this is also not entirely true as it really depends on how that particular cultivar was cultivated, there can be bananas that come directly from M. acuminata parentage and still be a plantain type banana. I hope this clears some things up.

This is interesting. But I'm now a little confused about cooking bananas (which apparently must be cooked) and plaintains, which should be cooked, but if they aren't, they become like dessert bananas -- sweet, to be eaten ripe without cooking. This is what I understand from you answer. So, is that the only difference between the cooking bananas and plaintains? That the former has to be cooked, while the other can be but it isn't mandatory to cook it? What happens if one eats a cooking banana without cooking it? Does it taste bitter in some way? Also, what are the distinctions between "half-plaintain" and "full-plaintain"? The gist seems to be, they're all bananas, I never realized that there were such precise distinctions.

There are also lawn and field plants that grow in temperate climates which are called "plaintains", and are nothing more than weeds. They don't produce fruit, as far as I know. I take it these are different plants, entirely?

I wouldn't worry too much about the difference between a cooking banana and a plantain, there really is no difference between any of the bananas (plantain, dessert, whatever), its more how you use that particular cultivar. Like the 'Orinoco' banana is also called 'Burro', because it is versatile like a Burro (donkey), they can be cooked or fried and used like a plantain type banana or be eaten raw when fully ripe. And what are called plantains are often harvested before ripeness then used, whereas the cooking bananas really need to be cooked at any stage and dessert bananas dont make good cooking bananas at any stage and are only good for eating ripe usually. The real difference between all of these is starch content, to put it simply, they are either potato-like with lots of starch (cooking bananas and unripe plantains) and those with very low starch content which are the tasty dessert bananas, so eating a raw cooking banana or an unripe plantain will be something like eating a really hard raw potato. But as I mentioned above, there is no clear distinction between any of them, one cultivar may fit into a few different catagories depending on how its used and what stage its in, its more opinion based then anything else. The other plantain you are thinking of is called Plantago major and is no way related to bananas, its just a common weed (however I hear its great for rashes and can be used like spinache).

Thanks. I've learned something.