A spore atlas of New Zealand ferns and fern allies

Abstract

This work constitutes a detailed study of the spores, of the ferns and fern allies, both native and adventive, which grow in New Zealand, from the Kermadec Islands in the North, to the Chatham Islands in the East and the Subantarctic Islands in the South. Twenty live families with sixty five genera, two hundred and eleven species (of which c.20 are introduced) and three subspecies are included. Seven species are heterosporous the remainder are homosporous. Trilete spores are found in c.104 species representing c.30 genera. Perine is present in most taxa (with the exception of Gleichenia) and ranges from the large and sac-like form as seen in Cyathea smithii, to the thin and reduced form seen in Adiantum. Monolete spores are found in c.109 species representing c.37 genera (two genera are included twice, Isoetes which has trilete megaspores and monolete microspores and Lindsaea which has both monolete and trilete species). Perine is present in most taxa (except Sticherus spp.) and ranges from a fine deposit as seen in the Psilotaceae, to an enlarged form, heavily winged, as seen in the Aspleniaceae. Sculpture in all taxa (with the exception of the Lycopodiaceae and some members of the Ophioglossaceae, which may have ornamentation distributed distally), is present on both distal and proximal faces. One adventive taxon Equisetum arvense L. has an unusual circular laesura and elaborate elaters. Light micrographs of acetolysed and fresh spores along with scanning electron micrographs, are included for each taxon. Keys presented, are based on gross spore morphology and are applicable to fresh and acetolysed material. Descriptions include a list of synonymous species, details of spore shape, laesura/ae details, perine/exine sculpture and thickness (where sections allow), size (measured from n=50 spores per population), for samples treated with cotton blue (lactophenol aniline blue formula), mounted in glycerine jelly and acetolysed samples, mounted in silicone oil. Percentage size differences for acetolysed material mounted in glycerine jelly are also noted, along with previous spore dimensions recorded in the literature. Descriptions also contain chromosome number, where known, a list of previously recorded descriptions, a brief indication of geographic location and a list of vouchers for each sample. Experiments on the size and morphology of fern spores in reaction to different preparation techniques are discussed. Fresh spores of seven species, four trilete (Adiantum fulvum, Cyathea smithii, Hymenophyllum flabellatum and Lycopodium volubile) and three monolete (Blechnum chambersii, Paesia scaberula and Tmesipteris elongata), were assessed wth regard to the effect of three standard pretreatments (lactophenol aniline blue, 10% KOH, acetolysis) and two mounting media (glycerine jelly and silicone oil). Changes in morphology and size of the various wall layers were noted in comparison to spores observed fresh in water. Results indicate that variation includes shrinkage e.g. silicone oil and expansion of both exine and perine in glycerine jelly. Both effects are modified by previous treatments.