Studies on the New Zealand, and some related, species of Pteris L.

Abstract

Four New Zealand species are recognised: (1) P. tremula R.Br., (also in Australia, Lord Howe Is., Norfolk Is., the Kermadecs Is. and the Chatham Is.). (2) P. carsei sp. nov. (previously ‘P. comans’) (also in Australia and the Kermadec Is.). (3) P. macilenta A. Rich. (previously P. macilenta var. saxatilis Carse) endemic. (4) P. pendula Col. (previously P. macilenta Auct. non. Rich. and P. macilenta var. pendula (Col.) Cheeseman) endemic. The taxonomy and nomenclature of these species is discussed in detail and the nomenclature is also discussed for P. kingiana Endl. (previously sometimes treated as P. tremula) and P. zahlbruckneriana Endl. (previously treated under ‘P. comans’ or P.endlicheriana Agardh) both Norfolk Is. endemics, and the taxonomy of P. sp.aff.comans LHI (previously ‘P. comans’) endemic to Lord Howe Island is also discussed. Detailed study of the spores and paleae using conventional light microscopy and SEM was made for these species and also P. comans Forst. f. (from the New Hebrides) and P. novae-caledoniae from New Caledonia. Comparisons of the distribution, fronds, stipes, venation, rhizomes, paleae, indumentum, apices, sori, sporangia and spores have been made and where appropriate material of P. dentata ssp. flabellata, P. pacifica and P. vittata, has also been compared. Further comparisons have been made with material of ‘P. comans’ from other Pacific Islands including Fiji (three species ), Rarotonga, Samoa, Tahiti (each one species). P. tremula, P. kingiana and P. novae-caledoniae are exceptional in the genus because they lack paraphyses in the sori. P. kingiana and P. novae-caledoniae have a copious waxy deposit around and among the sporangial stalks but P. tremula has no accessory sporangial features at all. Germination and gametophyte growth follow the normal pattern for the genus. Some gametophytes can be kept alive and growing for considerable periods (up to three years) and become elongate, ribbon-like and unisexual (female). Hybridisation was achieved between P. carsei and P. macilenta. The progeny resemble the natural hybrid swarms suspected of being the product of the same parents.