01521nas a2200145   4500008004100000245008600041210006900127260001200196300001300208490000700221520099800228100001501226700001701241856011701258       2005                        eng d00aComparative morphology of the glossopodia of three North American Isoetes Ligules0 aComparative morphology of the glossopodia of three North America  c2005///  a94 - 1140 v953 aOne of the most distinctive features of the heterosporous lycopsids is the presence of a ligule. This structure, currently found only in Isoetes and Selaginella, is comprised of a basally embedded glossopodium and a free distal tongue. Previous studies on Indian species have demonstrated small variations in glossopodia suggesting the possibility that this structure could have taxanomic use. Serial cross, paradermal, and sagittal sections of glossopodia from three different North American species, representing three ploidy levels, were made. Three-dimensional digital rendering of the glossopodia provided comparative data for the three North America species and allowed comparisons with previously published descriptions. In general, the shape of the glossopodium is similar in all three North American species. There are several structural differences among them, such as the shape of the cornua, the length of the medimoles, and the angle of the glossopodium relative to the leaf axis.1 aShaw, S.W.1 aHickey, R.J.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-27844529330&partnerID=40&md5=9334fdaf0c080402ef9a0ccef97c921001453nas a2200217   4500008004100000245010000041210006900141260001200210300001400222490000700236520073900243653001500982653001200997653001201009653002901021653001701050100001601067700001701083700001801100856011701118       2005                        eng d00aAnalysis of morphological and anatomical characteristics of Isoetes using isoetes tennesseensis0 aAnalysis of morphological and anatomical characteristics of Isoe  c2005///  a167 - 1820 v573 aThe three known populations of Isoetes tennesseensis were examined to document and analyze their morphological and anatomical characters. Characters examined included velum coverage, lacunae, leaf form and size, sporangial wall cells, and ligule and labium morphology. Three types of morphological patterns were found: stable, variable, and dimorphic. The discovery of dimorphism between mega- and microsporophylls for velum coverage, velum length, sporangium size, and ligule shape is of particular interest. This study presents a model for future work designed to complement current species descriptions and it establishes a baseline for morphological comparisons with other Isoetes. © 2005, by The New York Botanical Garden Press.10aDimorphism10aIsoetes10aLycopod10aMorphological characters10aPteridophyte1 aBudke, J.M.1 aHickey, R.J.1 aHeafner, K.D.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-21744447722&partnerID=40&md5=10d5e4181461bf404f341ea4a32c4740