Johnson , Anne Kathleen , Rothfels, Carl , Grusz, Amanda , Sigel, Erin , Windham, Michael , Pryer, Kathleen .
Sporophytes and gametophytes of notholaenid ferns (Pteridaceae) show correlated presence/absence of farina.
The "notholaenids" comprise a monophyletic group of New World ferns commonly characterized by the presence of farina on the abaxial leaf surfaces of the sporophytes. Farina, a whitish or yellowish waxy exudate produced by glandular hairs, is thought to be an adaptation to xeric habitats. During unusually dry conditions, the leaves of notholaenids curl up to expose their farinose undersides, reducing water loss by increasing reflectivity. All species of the notholaenid clade previously investigated have scattered farina-producing hairs on their gametophytes as well. This has been interpreted as a potential synapomorphy for the genus Notholaena because no other ferns display farina in both the sporophytic and gametophytic phases of their life cycle. Recent phylogenetic studies demonstrate that two species with non-farinose sporophytes (Cheilanthes brachypus and Cheiloplecton rigidum) are well-nested within the notholaenids, and a third non-farinose species (Cheilanthes leucopoda) is strongly supported as sister to all other notholaenids. This raises the question: are the gametophytes of these three species farinose like those of their close relatives, or are they glabrous? Here, we assay the gametophytes of a broad sample of notholaenids--including all three species with non-farinose sporophytes--to determine if the presence/absence of farina is correlated across the gametophytic and sporophytic phases of the life cycle for notholaenid ferns. Our survey of cultivated gametophytes indicates that species with non-farinose sporophytes also have non-farinose gametophytes. All other notholaenids sampled exhibit farina-producing hairs on the gametophytes. Thus, while farinose gametophytes are not upheld as a synapomorphy for the notholaenid clade, these desert ferns are consistent in their farina production across both phases of their life cycle.
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1 - DUKE UNIVERSITY, Department Of Biology, BOX 90338, DURHAM, NC, 27708, USA
2 - Duke University, Box 90338, Durham, NC, 27708, USA
3 - Duke University, Department Of Botany, Box 90338, Duke University, Durham, NC, 27708, USA
4 - Duke University, Science Drive, Durham, NC, 27708-0338, USA
alternation of generations
Presentation Type: Poster:Posters for Sections
Location: Khorassan Ballroom/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 5:30 PM