Q.No Question, Chokecherry Unrelated To Ponderosa Pine. At Least Willow In Different Family.
Different groups (dicot vs gymnosperm), different families (Rosacea vs Pinaceae). Your people should at least go to USDA website (to verify other plants listed). Willow family is Salacaceae. The poor research at your website makes me believe you don’t “know how”.

Certified GKH Gardening Expert
Thank you for bringing this to our attention. It was intended to be a list of trees that are compatible with the tree, rather than a comparison of relation. This article is being corrected.