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Farina Production by Gametophytes of Argyrochosma nivea (Poir.) Windham (Pteridaceae) and its Implications for Cheilanthoid Phylogeny
Jose María Gabriel, Jose María Galán and Carmen Prada
American Fern Journal
Vol. 102, No. 3 (July-September 2012), pp. 191-197
Published by: American Fern Society
Stable URL: http://www.jstor.org/stable/41809936
Page Count: 7
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Modern molecular phylogenetic studies of the Pteridaceae have recognized a well supported cheilanthoid clade that includes four major subclades: myriopteroids, pellaeoids, hemionitidoids and notholaenoids. Many of the morphological characters used in delimitation of the cheilanthoid lineages and genera appear to be the result of convergent evolution, a result of adaptation to xeric environments. Faced with the apparent lack of sporophytic synapomorphies for the cheilanthoid subclades, farina production by gametophytes has been proposed as a character of possible phylogenetic utility. All the notholaenoid species observed to date produce farina in their gametophytes, but species of the other cheilanthoid clades (pellaeoids, hemionitidoids, and myriopteroids) do not. In this work we provide the first account of farina production in the gametophyte of a non-notholaenoid: two accessions of Argyrochosma nivea from different geographical localities were found to have farina on their gametophytes, suggesting that this gametophytic character is not a synapomorphy for the notholaenoids, and may have had several independent evolutionary origins.
American Fern Journal © 2012 American Fern Society