The male sterility of the parent is very likely inheritable but it is affected by the cause of the sterility (genetic composition, chromosomal, or cytoplasmic causes) and if the parent is truly male sterile or just pollen poor.

Here is a link that might be useful: Mert & Soylu, 2006

Siblings, seedlings from the same mother tree, may trigger self recognition and NOT pollinate each other. Chestnut is pretty variable in its fertility with self and siblings. Collossal is a EuropeanXJapanese hybrid, I think, and crosses between two species are often male sterile. I know that American chestnut, pollinated by Chinese chestnut, makes nuts that grow up to be male sterile. It seems to be the American cytoplasm is not compatable with the nuclear genes of the Chinese parent, as crosses the other way around are male ferile. (Chinese mother tree, American father tree). If this was the case in Collossal, then your hope with the seedlings is that some of the crosses get the right cytoplasm to be fertile, and without knowing the male parent of the seednuts you are buying, it's a gamble. Some gambles pay off though, and you could hedge your bets by buying a known good pollinator and planting it upwind of the group of Collossal seedlings. If blight is not an issue for you, American chestnut is a good pollinator. If blight is an issue, try Chinese....or Japanese.

Well, good thing I ordered a pound each of Collosal, Sleeping Giant, Skookum, and Conn. Early! Out of that mix, they should pollinate.

Yes, it sounds like you will be OK. Sleeping Giant and Skookum are hybrids that are mostly Chinese, perhaps with a little European in them, so they should be OK with Collosal. I don't know Conn. Early, so can't say anything.

Jocel, I notice you mention being downwind for pollination. My chestnuts are loaded with native bees and flies when they are in bloom. Isn't this the primary source of pollination for chestnuts?

I don't know the answer to your question, but if you are in SE MN, maybe check out Badgersett nurseries in Canton. They seem pretty knowledgeable, they specialize in nut crops, and the genetic stock is local (MN weather) and I know they test their stuff against blight. I don't think blight has hit out in Washington yet.

Chestnut pollen is heavy and doesn't blow that much, but downwind trees have more nuts than upwind trees. There are three trees in the Public Gardens in Halifax, Nova Scotia, and the most upwind one has many fewer nuts than the most downwind one. Wind helps, so might as well use it.

Jocelyn

Corkball: Funny you mention Badgersett, because I'm already working on my order from them as well for a few hybrid chestnut and hybrid hazel seedlings. I already have a dozen hybrid chestnut seedlings from Oikos Tree Crops out of Michigan planted in the garden as well. There's also a nursery near Rochester called True Nature Farm that carries MN-hardy chestnuts that I still have to order from. Basically I'm working on getting as many sources of genetic material as possible to populate my property with, because my long-term plan is to start growing and giving away as many hybrid chestnut seedlings as possible to whoever wants them for wildlife habitat and edible landscaping in my area.

Harvestman: I also thought chestnuts were primarily wind-pollinated, but my Bosnian coworker told me that on the farm he grew up on, the stands of European chestnuts were heavily visited by bees when in bloom. Interestingly enough, he also said chestnut pollen would create honey with a reddish tint to it!

OK, now that I'm thinking about this some more, I think pollen sterility might create a problem with what I had in mind if I can't tell definitively whether or not seed-grown offspring will also be pollen-sterile.
What I planned was to order 4 lb of chestnut seed from 4 different cultivars (approximately 120 nuts total), stratify in the garage over winter, plant them in discarded plastic containers I get from my QA lab (approximately 12" tall and 6" in diameter, used at the factory for 5-lb bulk cottage cheese and yogurt packaging, and the perfect size for tree saplings), and grow them until spring 2013 or 2014 in a protected, fenced-in portion of my garden. At this point, I'd select the most vigorous 10 saplings for my own yard, and give the remainder away to neighbors, friends, family, coworkers, posts on Craigslist, etc.

My thought was to give them away in pairs, with one pollen-sterile and one pollen-fertile cultivar each. However, if even seedlings of Colossal and Sleeping Giant are pollen-sterile, that means only one of the two trees in the pair would bear nuts, correct? For example, a Skookum would pollinate a Colossal, but then the Skookum wouldn't get any pollination itself. I could give them away as threes instead (one pollen-sterile, two pollen-fertile), but then people would probably just plant them too close together because not a lot of yards have room for 3 mature chestnuts. It just seems a waste to have a potentially fruitful tree not bearing because of a lack of a pollinator.

The seeds are already in the mail, so there's no going back now

If you have one male fertile tree, there is a pretty good chance that it will pollinate all the trees downwind. Some people plant three trees together, as a multitrunked clump. This makes a mature "tree" slightly larger than a single tree, and everybody gets pollinated. Don't do that if you are in a drought area, or you will have to water a lot. I don't know the climate and soil in your state, as I'm in Canada. Someone else will have to answer the question of whether seedlings of Collosal and Sleeping Giant are pollen fertile, and I suspect that it would depend on who the father tree is for each nut that grows up. You could get a pleasant surprise most of the time.