Studies in the genus Hypericum L. (Guttiferae) 4(2). Section 9. Hypericum sensu lato (part 2): subsection 1. Hypericum series 1. Hypericum

Introduction 61 Sect. 9. Hypericum 61 Subdivision 61 Characters and variation 61 Distribution and evolution 62 Sect. 9. Hypericum subsect. 1. Hypericum series 1. Hypericum 62 Characters and variation 62 Hybrids 64 Distribution and evolution 65 Systematic treatment 66 Sect. 9. Hypericum 66 Sect. 9. Hypericum subsect. 1. Hypericum series 1. Hypericum 67 References 119 Systematic index 121 The subdivision of the large sect. 9. Hypericum and four of its segregated sections having been treated in Part 4(1), Part 4(2) is concerned with those members of sect. 9, viz. Hypericum sensu stricto, in which the stem internodes have glandiferous raised lines – subsect. Hypericum series Hypericum . The series comprises 11 species and can be divided into (i) a group centred in Europe and the Mediterranean (4 species) and (ii) one centred in north-east Asia (6 species), one species of which is confined to western North America and another has spread westward into Europe. The remaining species ( H. perforatum ) is morphologically and geographically intermediate between two taxa, one from each group, and behaves as an allotetraploid hybrid. It is divided into four subspecies: subspp. perforatum , songaricum (Ledeb. ex Rchb.) N. Robson stat. nov. , veronense (Schrank) H. Lindb. and chinense N. Robson subsp. nov. The hybrids of H. perforatum are treated in detail and include H. × desetangsii nothosubsp. balcanicum N. Robson, nothosubsp. nov. ( H. maculatum subsp. immaculatum × perforatum ). Other new hybrids proposed are: H. × laschii nothoforma froelichii N. Robson, nothoforma nov. ( H. maculatum subsp. obtusiusculum × tetrapterum ), H. undulatum × tetrapterum and H. elegans × perforatum .