History of perennial onion varieties

I'm interested in learning more about the origin and history of perennial onions, including potato onions, shallots, walking onions, true scallions, and I'itoi.

What I find as I search the web is a lot of sites that quote each other, but none have footnotes back to an authoritative source.

I'itoi are one of the worst documented. Numerous sites say that Jesuits introduced them to the Desert Southwest in 1699, but that clearly wasn't their origin. The Jesuits had to have gotten them from somewhere before they could introduce them! One site said that botanists have shown them to be related to clumping onions from Europe, but I have been unable to find any information on European clumping onions, especially not before 1699.

Potato onions and shallots were apparently introduced into Scotland by a Captain Burns around 1790. He also appears to have introduced the tree onion or walking onion, which can create confusion. The walking onion is commonly known as the Egyptian onion and was supposedly brought from Egypt to France during Napoleon's campaign in Egypt,  but other sources say their origin has nothing to do with Egypt. Apparently walking onions genetically originated from a cross between true scallions (Allium fistulosum) and common bulbing onions (Allium cepa).

True scallions are Allium fistulosum and will not form bulbs, but apparently some scallions being sold are actually Allium cepa bulbing onions, and are simply harvested and sold before the bulbs form.

And so it goes. There is a lot of conflicting, inconsistent information, and hardly anything that could be called a primary source.

Has anyone found good primary sources on the origins of the many perennial varieties of onion we have today?

Also, has anyone found a master database of heirloom onion varieties and cultivation methods, similar to what Tatiana's Tomato Base offers for tomatoes?

You might find some later details at the USDA ARS search page. Some items appear to be available, but that's mostly an illusion as they don't care to share. But the site has some research value. If you click on the advanced search you get the opportunity to include item's not currently available or no longer in the collection. They are most generous with apple scions unless they think you're a pest.

Good luck with your project.

Let me direct you to my thread on Potato Onions - this may be a good start for you.  If you haven't already read Kelly Winterton's papers on potato onions, you may find some of what you need there.

Potato Onions- the easy-to-grow perennial crop

Also there is the potato onion growers project... I think I have it linked in there. I don't recall if they have more history, but they might.

Good luck!