Developmental and Structural Section
Mickle, James , Lumaga, Maria Rosaria Barone , Moretti, Aldo , DeLuca, Paolo .
Micromorphological Insights on the Systematic Position of Bowenia and Stangeria (Cycadales).
Cycad cuticularmicromorphology was examined in Stangeria and Bowenia. Stangeria eriopus (Kuntze) Baillard is from Africa and has a subterranean stem with pinnate leaves whose leaflets possess a midrib. Bowenia serrulata Chamberlain and B.spectabilis Hooker are from Queensland, Australia and have subterraneanstems and bipinnate leaves. Some workers place these genera in the same family, Stangeriaceae, while others suggest that they are not as closely related. Foliar samples were taken from the middle of mature leaves from greenhouse-grown plants (Duke University; UniversitÃ di Napoli). Leaf material was fixed in FAA; cuticles were isolated in 20% Cr2O3 for up to 72 hours. Specimens were coated with gold-palladium and observed under SEM. Stangeria abaxial external cell surface is smooth, with scattered granulose particles and cell outlines partially visible. Stomata are on the same level as epidermal cells with a slightly elevated flange. Stomatal pores show raised lips extending Â¾ of guard cell length. Distinct striations extend to 0.1 mm from stomatal poles. Similar striations surround hair bases. Internally, surfaces of abaxial epidermal cells are felty, well demarcated, and intervenal cells are randomly arranged. Guard cell cuticles are in shallow pits and finely granulose. Thick flanges flank stomatal apertures. Short polar extensions are present. Stomatal complex is surrounded by a flange with serrate margin, felty inner surface and 5-6 divisions. Bowenia abaxial internal epidermal cell cuticle surface is lightly granular. Epidermal cells are well-marked, elongate and irregularly spindle-shaped. Cuticular flange between guard cells is thickened at the middle, giving it a diamond-shaped platform appearance. Stomatal opening extends 1/2 the length of stomatal apparatus. Adjacent to the cuticular flange, on either side, is an enlarged buttress with two diagonally-extended pegs. Laterally there is a low ridge on each side. Inner cuticular walls of guard cells is rugose. Polar extensions are flattened. Subsidiary cells are 5-6 and irregular, with two polar subsidiary cells. Stomatal long axes are aligned with epidermal cell long axes. Cuticular micromorphology does not show close similarity between these genera, supporting a more distant relationship of these genera.
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1 - North Carolina State University, Department of Plant Biology, Campus Box 7612, 2115 Gardner Hall, Raleigh, NC, 27695-7612, USA
2 - DIPT DI BIOLOGIA VEGETALE, VIA FORIA 223, NAPOLI, I-80139, Italy
3 - Orto Botanico, Via Foria 223, Napoli, 80139, Italy
Presentation Type: Poster:Posters for Sections
Location: Khorassan Ballroom/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 5:30 PM