Hi Linda,
Calylophus is no longer an accepted genus by plant taxonomists. For what it is worth, the species in this genus were all originally classified under Oenothera before being split out into Calylophus, sometime in the 70's I believe. They were recently lumped back into Oenothera (plants from the genus Gaura were lumped into Oenothera as well).
The real problem in this case is that nurseries often sell cultivars of Oenothera speciosa under the name Oenothera berlandieri. It is likely that somebody just made a mistake with the name when these plants were first released and it has been perpetuated over time. That happens quite commonly in the horticultural world. However, Oenothera speciosa has a well-deserved reputation for being an aggressive garden plant. Renaming plants with bad reputations, as a marketing strategy, is also fairly common in the horticultural world.
