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

Abstract

Introduction 61Sect. 9. Hypericum 61Subdivision 61Characters and variation 61Distribution and evolution 62Sect. 9. Hypericum subsect. 1. Hypericum series 1. Hypericum 62Characters and variation 62Hybrids 64Distribution and evolution 65Systematic treatment 66Sect. 9. Hypericum 66Sect. 9. Hypericum subsect. 1. Hypericum series 1. Hypericum 67References 119Systematic index 121The 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.