Caesar sent me 4 varieties a year ago (thanks!) I'm very motivated to find more diversity of the species. For me, air potatoes are second only to ulu (breadfruit) as a staple carbohydrate (my criteria are ease of growing, no soil disturbance, ease of harvest, ease of preparation, and availability.) Here's a report-back on what I've learned so far:
Mae-sai yellow: I planted 4. One vine made 50 or more small bulbils. After 3 20ish minute boils in changed water, they're still super bitter. I consider them inedible.
"very probably" (Caesar wasn't positive) Tefoe purple: I planted 4. I didn't compare the vines super closely to Caesar's photos, but at least superficially they do look like his Tefoe purple photos. At least one vine made several medium bulbils. The flesh is purple. If Joe Tefoe returns to this thread maybe he can say more, but in a listing where he's selling it, he says the edibility is unknown. But for me, as with Mae-sai yellow, 3 boils left them still super bitter and inedible.
CV-1: I received one small bulbil. The vine grew well last year but didn't make any bulbils. It's growing well again, so I should get some yield this year.
Saipan purple: I received one medium-small bulbil. The plant produced one large and several medium-small bulbils. I cut the large one in half to replant half (which is now shooting up vigorously). After the disappointments of Mai-sai yellow and the very probably Tefoe purple, and since Caesar described needing multiple boils of this, I expected I wouldn't find this variety useful. We already have the "Hawaii" variety here*, which only needs 20-30 minutes of steaming, so I wasn't motivated to do a careful trial with the Saipan purple. I boiled it for "a while" (maybe 30-40 minutes?), then tasted it expecting it to need a change of water and more boiling and thus for me to stop caring about the variety. But it had no bitterness! I didn't have any more bulbils I could try cooking, but I suspect it didn't need nearly as long a boiling as I gave it.
Needing to peel the tough skin off the Hawaii variety is the biggest drawback to this as a main staple. It's not *that* difficult or time consuming, but it is a drawback. My friends discovered that they can steam bulbils, then slice them thin and roast them with the skin still on, and the crispiness of it all makes eating the skin unnoticeable. So I wonder whether, even if the Saipan purple needs more cooking than Hawaii's 20ish minutes of steaming, the Saipan might work well steamed (or boiled), then sliced and fried to give it that extra cooking time. I should have lots of bulbils to test cooking requirements after this season.
For this season, I ordered what were listed as D. bulbifera from thailandplant
on Ebay. Caesar wrote that he got what he calls "Nonthaburi yellow" from them years ago, but I think he's lost that variety. This listing shows bulbils with white flesh, so not the same one Caesar got. But the seller confirmed that this one is edible after 30 minutes of boiling, so I ordered a batch. The seller sent 6 instead of just the 3 promised by the listing, and so far 2 have sprouted well; 1 rotted; and 3 still have a chance. However, the vine is D. alata, not bulbifera. I'm a little disappointed, but the pictures show decent sized bulbils, so I think this could still be a useful aerial crop.
I messaged with the seller about the species misidentification and asked about the one Caesar purchased, which isn't listed for sale at this time. The seller sent some pictures of what looks like true bulbifera, and said it's used by most people only for medicine, but is eaten by people in hill tribes. This variety has yellow or orange flesh, and though I'm not positive they're the same, the pictures do look like Caesar's Nonthaburi yellow. The seller wrote:
The hill tribes eat Dioscorea bulbifera because they eat anything they can find. For other people, they tend to eat Dioscorea alata because its taste is better and it can be cooked in various ways, both savory and dessert. Dioscorea bulbifera has to be roasted to eat and if you want to boil it, it literally needs to be boiled in 2-3 changes of water as you said. So if you would like the one that is easy to cook, I recommend Dioscorea alata. You can boil it for only 20 minutes. Or if you boil it with coconut milk and add some sugar and pandan leaves, it's delicious.
So I don't think the Nonthaburi yellow is worth reacquiring.
Priorities for reacquiring seem to be CV-2, Sena, and Odisha yellow as known good edible types. "Mexico" and "Africa" might be good too, though there isn't enough info in Caesar's posts to know much about them.
I'm not able to send out air potatoes at this time. But I expect to be organized for selling seeds and corms and bulbils of various species by the end of the year, so can help then with spreading the varieties I have.
Interwoven Permaculture sells a few different Dioscorea bulbils, including "Hawaii" bulbifera (2 for $35).
And a tangential share: Our "Hawaii" variety starts making immature but yummy bulbils in July, which you can pick from the vine. Fully mature bulbils drop on their own from about November through February. Another friend found that he could keep stored bulbils edible until June by breaking off any shoots once a week. So with a little work, this is nearly a year-round crop!
* Note: I've lived in Hawai'i since 2012, and have only ever heard of one variety of bulbifera. Though I could be wrong, I believe that "Jim's Hawaii" and "Hawaii" and the one that's common in my area are all the same.
