In some of these classifications, this and other hybrids of Nootka cypress become very unusual in being intergeneric hybrids, the only ones ever reported among the gymnosperms. In 2010, Mao et al. performed a more detailed molecular analysis and redefined "Cupressus" to exclude "Chamaecyparis", but to include the Nootka cypress. It may be added that attempts to cross Nootka cypress with other "Chamaecyparis" species have been universally unsuccessful. The scientific name of Leyland cypress depends on the treatment of Nootka cypress. Where Nootka cypress is considered as "Cupressus nootkatensis", the hybrid is within the "Cupressus" genus and is therefore "Cupressus" × "leylandii". If both Monterey and Nootka cypress are considered as species of "Callitropsis", the hybrid is "Callitropsis" × "leylandii". However where the parents are treated as being in different genera, Leyland cypress becomes an intergeneric hybrid: if Nootka cypress is within "Chamaecyparis", the name of the hybrid becomes ×"Cupressocyparis leylandii", and where it is treated as "Xanthocyparis", the hybrid becomes ×"Cuprocyparis leylandii".