Seems likely. Siberian Elm will actually naturally hybridise with Native Red Elm. Elm hybrids do not otherwise occur as a rule due to different times of year for seeds to develop.
Good to know, PatM.I can spot an elm from half a mile at a glance, but it gets a lot fuzzier from there They were clearly different species, by neighbors, wood, and bark, but growing at each end of a couple hundred yard thicket.
When the Mormon pioneers came to Utah they brought a lot of species out with them for shade and ornamental trees, as well as fruit trees, etc. Black and yellow locust, maples, sycamores, and very rarely osage and hickories. This thicket had the rotting remains of three huge old "mother" tree stumps along the edge of a field, and even the stumps look like different varieties with the thickets of small to medium volunteer all along the ditch and fence. They LOOK like two of the good kind and one of the other.
But, it seems like little volunteer Siberian elms pop up everywhere you let them, even sidewalk cracks. I see them on the sides of the roads from Frida to Texas, to Oregon when I travel, and a lot of people would have access to it if you can find a ditch line or vacant lot. Again, if you have nothing else.
