セント・ジョーンズ・ワート
It is probable that "Hypericum perforatum" originated as a hybrid between two closely related species with subsequent doubling of chromosomes. One species is certainly a diploid a subspecies of "Hypericum maculatum", either subspecies "maculatum" or "immaculatum". Subspecies "maculatum" is similar in distribution and hybridizes easily with "Hypericum perforatum", but subspecies "immaculatum" is more similar morphologically. The other parent is most likely "Hypericum attenuatum" as it possesses the features of "Hypericum perforatum" that "Hypericum maculatum" lacks. Though "Hypericum maculatum" is mostly western in its distribution across Eurasia and "Hypericum attenuatum" is mostly eastern, both species share distribution in Siberia, where hybridization likely took place. However, the subspecies "immaculatum" now only occurs in south-east Europe.