Beauty is found in almost any maple tree, even if we are to consider only their colourful fall display. The Beast shows its ugly head especially in the case of trifoliate maples and is called parthenocarpy. As a remainder, this means production of seedless fruits (without the fertilization of ovules).
A really undesirable trait, especially for species with indehiscent fruits (samaras, nuts, achene), either if we want their seeds for consumption or to use them for propagation! This is also the explanation for the rarity of some magnificent tree species in our landscapes. Acer griseum, the best known of the trifoliate maples presents parthenocarpy to some extent but not as much as the beauty called Acer triflorum.
I did a little experiment with about the 60 seeds I had and a pruning shear. By nicking the end of the extremely hard samara and then cracking it longitudinally you can extract the seeds, if any. I found 3 viable seeds and 3 aborted (stenospermocarpy) – about 5% viable seeds!
PS. One easy method to separate seedless fruits is to check if they float; the ones with seeds will go to the bottom. This is recommended for many species when we actually sow the fruits (like samaras and nuts) and it is hard to say if there are any seeds inside.
The fruit wall is so hard in Acer triflorum that it needs lots of stratification just to wear it down, so I preferred to extract the seeds (I didn’t expect to find any, but perseverance paid off :)