Our mystery seeds from the orange "berries" last week were from a mountain ash tree, Sorbus sp.
Mountain ashes are small trees that are popular in landscapes.
The orange fruit, which grow in clusters, are eaten by birds. This photograph of the fruit was taken in October.
I thought probably the tree I took the seeds from was the American mountain ash, Sorbus americana, which grows in northeastern North America.
However, these American mountain ash seeds by Steve Hurst @ USDA-NRCS PLANTS Database have a pronounced hook at the ends. They are also relatively longer and narrower.
The seeds look closer to Sorbus hybrida, which is the oakleaf mountain ash (Photograph by Tracey Slotta @ USDA-NRCS PLANTS Database). On the other hand, the leaves and geographical distribution are all wrong.
What do you think about Sorbus scopulina, called Greene's mountain ash (photograph by Steve Hurst @ USDA-NRCS PLANTS Database)? These are from western North America.
In all likelihood, these landscape trees are a cultivated variety that doesn't match any of the above. They will remain a bit of a mystery, after all.