An isolated population of trees in the New York Mountains of southeast California with needles mostly in pairs, previously thought to be Colorado Pinyons, have recently been shown to be a two-needled variant of Single-leaf Pinyon from chemical and genetic evidence.
An isolated population of Single-leaf Pinyon trees in the Mojave Desert's New York Mountains, within the Mojave National Preserve of southeast California, has needles mostly in pairs and was previously thought to be Colorado Pinyons. They have recently been shown to be a two-needled variant of Single-leaf Pinyon from chemical and genetic evidence.