All just Calystegia sepium? Calystegia-Hybrids in Aachen

In the genus Calystegia, a frequent hybridization is well known. Meanwhile, various taxa are considered hybridogenous. In the municipal area of Aachen, variable, apparently hybridoge-nous populations can be observed, which suggests far-reaching introgression. They are at least independent of one parental species, whereby the occurrence of the other possible pa-rental subspecies C. sepium subsp. sepium appears questionable and an exclusive occurrence of hybrids is realistic. Minor hairiness of young shoot tips and the leaf sinus as well as rare square leaf sinuses could indicate C. pulchra as parental species and thus the presence of C. ×scanica. Maybe C. sepium subsp. sepium can also be more frequently slightly hairy than known and then C. silvatica is the possible other parental species and accordingly, C. ×lucana is present. However, other parental taxa are conceivable. Therefore, no assign-ment to described species or hybrids can be made in the study area. Two clans can be distin-guished there. Especially because of flower characters, one is habitually more similar to C. pulchra or C. silvatica, while the other overall resembles C. sepium subsp. sepium, but dif-fers in several features. Both are common in the study area. Their features are presented herein as well as their origin is discussed.