The morphological and chemical data together with the field observations indicate that, at least in northern Michigan, P. longiligulatus is indeed a hybrid between P. strictifolius and P. zosteriformis. However, one question remaining unanswered is the mode of origin of the hybrid. The entity could be either 1) sterile hybrids of recent and occasional origin and, thus, not a distinct species; or 2) a distinct species that is reproductively isoldated from the parental species and that originated through hybridization at some time in the past. The question is apparently unanswerable until more is know about the reproductive biology of the hybrid.