Phloroglucinol derivatives in Dryopteris sect. Fibrillosae and related taxa (Pteridophyta, Dryopteridaceae)

The phloroglucinol compositions of 18 species (including subspecies) belonging to Dryopteris Adanson sect. Fibrillosae Ching have been investigated on a world-wide basis, and the taxonomic implications discussed. The main emphasis is on D. affinis (Lowe) Fraser-Jenkins, its subspecies and varieties, as well as on D. wallichiana (Sprengel) N. Hylander and its relatives. The phloroglucinols of the ferns of sect. Fibrillosae proved to be remarkably constant in most taxa: large amounts of flavaspidic acids (5) and slightly varying amounts of filixic acids (19) were found in virtually all taxa. Traces or small amounts of norflavaspidic acids (4), albaspidins (10), oligoflavaspidic acids (23, 26) and tetraalbaspidins (25) occur as well. Only D. acutodentata Ching and D. affinis subsp. borreri (Newman) Fraser-Jenkins, both partly derived by crossing with species outside the section, differ clearly from the other taxa in containing para-aspidins (7) and trisparaaspidin (20), while D. fusco-atra (Hillebrand) W. Robinson shows a different phloroglucinol pattern altogether. The high levels of similarity between taxa may reflect their common origin from a few diploid apomictic taxa by hybridization with sexual diploids. The different subspecies and varieties of D. affinis showed very similar phloroglucinol spectra except for subsp. borreri. The triploid apogamous subspecies cambrensis Fraser-Jenkins, pseudo-disjuncta (Fraser-Jenkins) Fraser-Jenkins and persica Fraser-Jenkins may have evolved from the diploid apomictic subsp. affinis and D. oreades Fomin of sect. Dryopteris, whereas the triploid apogamous subsp. borreri may have its origin from subsp. affinis and D. caucasica (A. Braun) Fraser-Jenkins & Corley of sect. Dryopteris. The precursor of apomictic diploid D. wallichiana subsp. wallichiana is discussed. Dryopteris crassirhizoma Nakai, a diploid sexual species from Japan in sect. Fibrillosae, is suitable from a chemical point of view, but not from its morphology. Dryopteris conjugata Ching in sect. Hirtipedes Fraser-Jenkins initially appeared to be suitable both in morphology and chemistry, provided that norflavaspidic acid (4) was biotransformed to flavaspidic acid (5) in D. wallichiana subsp. wallichiana as suggested in the present work. However, cytological investigation of one accession of this species has shown it to be diploid but apomictic, and therefore inappropriate as a sexual diploid ancestor of the diploid apomictic D. wallichiana subsp. wallichiana