These differences might be a reflection of a sampling bias caused by missing nuclear genotypes, particularly for individuals in AH. File:Alsophila — Wikimedia Commons Breeding systems of three tree fern species: ATL is found in an unprotected cloud forest patch of c. Significant SGS was evaluated by testing the regression slope of R L on the logarithm of distance b R with alsopbila replicates. Worldwide distribution of Cyatheaceae based on data from Encyclopedia of Life www. The location of individual stems was carefully mapped using the distance m and compass bearings between individuals, thus obtaining the relative spatial coordinates of each individual. These proposed lineages are separated by differences in scale morphology.

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Distribution Worldwide distribution of Cyatheaceae based on data from Encyclopedia of Life www. The extant scaly tree ferns are commonly found in the tropics, from the wet lowlands to mid elevations. However, some species are also found in high mountain areas in the tropics at elevations up to m Bystrikova, Ranil et al. Madagascar is an example of this pronounced local endemism, the island has 49 endemic species of scaly tree ferns Janssen et al.

Hymenophyllopsidaceae: The filmy, scaly tree fern The diminutive Hymenophyllopsis superba. Species of the genus Hymenophyllopsis are small plants with pinnate fronds, mostly cm long.

Their tissue is only cells thick with chloroplasts present only in epidermal cells and lacking in stomates.

The stems are usually short-creeping to sub-erect or erect. Hymenophyllopsis look superficially similar to filmy ferns Hymenophyllaceae because of the similar characteristics of the lamina.

However, this is likely to be the result of convergent evolution rather than a close taxonomic relationship. Image on right: Hymenophyllopsis dejecta specimen. Image attributed to Intermountain Herbarium via intermountainbiota. Bystrikova et al. Along with the geographical isolation of the tepuis, it appears that the climatic conditions in the Roraima formation have facilitated the evolution of a group of plants with morphological adaptations very different to those normally associated to the scaly tree ferns.

The affinity of Hymenophyllopsis with Cyatheaceae had been suggested but has only been confirmed in recent years through phylogenetic studies Wolf et al. Recent studies suggest strongly that Hymenophyllopsis nests within Cyathea as they both share marginal scales without apical setae and cyatheoid cup-shaped indusia Korall et al. More recently, Hymenophyllopsis has been described as a subgenus within Cyathea Christenhusz, The generic limits of Cyatheaceae Generic delimitations of Cyatheaceae have differed substantially across various studies and have been hotly debated in recent years.

However, with evermore phylogenetic analyses and data botanists are beginning to piece together that main groups or genera within the family. In a later study, Stein et al. This study moved Cnemidaria and Trichipteris which nested within Cyathea, and Nephelea now nested within Alsophila. Alsophila was reclassified to include ca. These proposed lineages are separated by differences in scale morphology. In the most recent phylogenetic study, Korall et al.

References Bystriakova, N. Evolution of the climatic niche in scaly tree ferns Cyatheaceae, Polypodiopsida. Botanical Journal of the Linnean Society, , Christenhusz, M. New combinations and an overview of Cyathea subg. Hymenophyllopsis Cyatheaceae. Janssen, T. Neoendemism in Madagascan scaly tree ferns results from recent, coincident diversification bursts. Evolution, , Korall, P.

Tree ferns: Monophyletic groups and their relationships as revealed by four protein-coding plastic loci. A molecular phylogeny of scaly tree ferns Cyatheaceae. American Journal of Botany, 94, Lehnert, M. Three new species of scaly tree ferns Cyathea-Cyatheaceae from the northern Andes. Morton, C. American Fern Journal, 22, Pryer, K. Phylogeny and evolution of ferns Monilophytes with a focus on the early leptosporangiate divergences.

American Journal of Botany, 91, Ranil, R. Conservation priorities for tree ferns Cyatheaceae in Sri Lanka. Taiwania, , Schuettpelz, E. Fern Phylogeny inferred from leptosporangiate species and three plastid genes. Taxon, , Smith, A. A classification for extant ferns. Sporne, K. The morphology of pteridophytes. Stein, D. The implications of chloroplast DNA restriction site variation on the classification and phylogeny of the Cyatheaceae.

Johns [ed. Tryon, R. The classification of the Cyatheaceae. Gray Herb, Wolf, P. Phylogenetic relationships of the enigmatic fern families Hymenophyllopsidaceae and Lophosoriaceae: evidence from rbcL nucleotide sequences.

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Cyatheaceae: The Scaly Tree Ferns






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