Oooh, hazel nuts, yummy. Awesome for pollen. We have several growing in our yard, some older a few younger, we never ever get any nut. We have two species of squirrels here and between the two of them, the Stellar jays, and who knows what, I never gather a single nut. I do see the shells. I have gone out to a neighbouring town in an old mostly abandoned area of a park up on a great big grassy hill that has an enormous grove of hazelnut trees, wish it was closer to my home, cause we gathered nuts til we could carry no more. Grow on the hazelnut saplings, they grow quite quickly!! I think that the alder trees that grow in profusion around our place are incredible for pollen. I do not know that for sure, but I think they would be. On my patio deck outside my bedroom, when it rains, I take the opportunity to wash this deck with a sponge mop that I leave out there for that purpose. In the spring the pollen that I wash off this deck is beyond your wildest dreams. The sponge water is incredibly greeny looking. I never thought about alder and pollen, but I see the catkins long before the different species of maples are producing pollen. Great day...Cindi