Two years ago, I planted some Babbington's Leek topsets similar to the ones you see on this flowerhead. They don't produce seed; garlic can be persuaded to do so, but I don't know whethre anyone has ever tried with Babbington's. this year they flowered. I got them well and truly mixed up with some elephant garlic bulbils I planted at the same time, and ended up with only four Babbington's; the two plants look very similar above ground, and even below it until the elephants get big enough to clove. Never mind; I lifted the Babbington's yesterday, and each bulb had divided into two, about 2 1/2 inches or so across. So I now have eight Babbington's for next year, plus the topsets.
It's an interesting plant, which seems to have abandoned sexual reproduction altogether. This can happen in the wild, but also happens in cultivated plants. We select for the maximum crop, and in the process, we select plants which don't put their energy into reproduction. Seed merchants, of course, push the process in the opposite direction, as they want to sell seeds, which are much easier to handle than plants. So a lot of these are now obscure heirlooms. Babbington's grows wild in a few places, on the Isle of Lundy for instance, and we don't even know whether it's a wild or a cultivated plant. It produces reasonable shanks for a lot less effort than 'normal' seed-grown leeks, so it's worth persevering with.
I put it into the new allium bed, alongside the walking onions. I have five varieties, which I acquired last year, but I'm not saying much about these until I've grown them for a year from full-sized bulbs rather than topsets. That's my excuse anyway; the bed I've had them in has been too weedy for decent pics. It was a new one, and it takes me a a year or two to get the ground elder out, digging them over between crops. So far there's not all that much to choose between the varieties, though there are recognisable differences, and I'm quite pleased with their progress so far.
I've also put in two varieties of garlic. It's very early, but it'll sit there quite happily until it decides to sprout in the autumn. It's all intercropped with dwarf beans to make the best use of space which will remain limited until I manage to build raised beds across the entire plot.
Other perennial alliums are flowering rather than making topsets. This one's yellow potato onion; they've all topples over, and this one is reclining on ulluco. I've also got flowers on white potato onion and the odd shallot, which is of course also a potato onion. I've grown some spud onions (Green Mountain) from seed this year; they were planted late, the fox dug a fair few up as soon as they were planted out, but the survivors are doing well, if not spectacularly. I've got a lot more seed which will go in early next year. This one's my best, with a bulb about 2 1/2 inches across.
I don't think there's much difference between potato onions and the ordinary sort; one has been selected to be a biennial which produces plenty of seed, the other to be a perennial which produces little or none, but reproduces vegetatively, with each bulb dividing into a clump. This has never entirely been my experience; I've always had plants flowering, though previously I've done the conventional thing and pulled the flowers off.
The problem with shallots and other potato onions is probably that viruses accumulate over the generations, leading to stunted bulbs. Raising a generation from seed breaks this, frees them from virus, and gives (or so I'm told) bigger onions. I'm going to keep experimenting with seeds, and see where I end up.
These fabulous purple blooms belong to elephant garlic and perlzweibel, a small perennial leek, respectively. the elephants, of course, are another leek, with a root which splits like garlic, and a mild garlic taste. Hopefully, more seeds to play with next year! I've no idea what sort of fertility to expect; I planted everlasting onion this year, and only got one plant, which came up after about a month. I've got a lot more seed to put in next year.