01098nas a2200205   4500008004100000245007300041210006500114260001200179300001400191490000700205520044400212653001000656653002700666653001600693653001400709100002100723700001500744700001700759856011600776       1996                        eng d00aThe microspores of Isoetes coromandelina (Isoetaceae : Pteridophyta)0 amicrospores of Isoetes coromandelina Isoetaceae Pteridophyta  c1996///  a101 - 1080 v153 aThe study of microspores of different populations of I.coromandelina has revealed that microspores may be monolete or trilete exhibiting considerable variation in size and shape within one and the same sporangium. The perispore may be loose or closely appressed to the exospore. Their surface ornamentation is invariably echinate but the length and the concentration of the spines and their arrangement may differ in different populations.10aIndia10aIsoetes coromandealina10aMicrospores10aperispore1 aSrivastava, G.K.1 aPant, D.D.1 aShukla, P.K.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-1542575449&partnerID=40&md5=9106c9d98b0da94ab52a9c1258e7246702381nas a2200253   4500008004100000245013000041210006900171260001200240300001600252490000700268520155900275653001501834653001101849653001201860653002101872653001201893653002301905653001501928653002201943100001701965700001701982700001201999856011602011       1996                        eng d00aBiosystematic studies on the genus Isoetes (Isoetaceae) in Japan. II. Meiotic behavior and reproductive mode of each cytotype0 aBiosystematic studies on the genus Isoetes Isoetaceae in Japan I  c1996///  a1309 - 13220 v833 aMeiotic behaviors and reproductive modes of Japanese Isoetes were studied. The hexaploid (2n = 66) and the octaploid (2n = 88) of I. japonica consistently formed 33 and 44 bivalents, respectively, at diakinesis and/or metaphase I in both micro- and megaspore mother cells. The tetraploid (2n = 44) of I. sinensis formed 22 bivalents and its hexaploid made 33 bivalents in both types of spore mother cells. At diakinesis and/or metaphase I of microspore mother cells in I. asiatica with 2n = 22, 11 bivalents were detected. Because behaviors of meiosis in all cytotypes mentioned above were quite regular and plants yielded normal-appearing spores, they should reproduce sexually. Aneuploids of I. japonica with 2n = 87 formed 43 bivalents and one univalent, and I. sinensis with 2n = 65 formed 32 bivalents and one univalent in microspore mother cells. Meiosis of both cytotypes was almost regular and yielded microspores of normal appearance. In the heptaploid (2n = 77) of I. japonica, a configuration of 22 bivalents and 33 univalents was detected in micro- and megaspore mother cells, and various irregularities were observed throughout the meiotic divisions. Therefore, the genomic formula of the heptaploid is symbolized as AABBCDE, and the heptaploid is a sterile F 1 hybrid between the hexaploid (AABBCC) and the octaploid (AABBDDEE) of I. japonica. Since diploid and even-numbered polyploids regularly formed bivalents and odd-numbered ones displayed irregularities, allopolyploidy should act as a significant speciation mechanism in this genus.10aChromosome10aHybrid10aIsoetes10amegasporogenesis10ameiosis10amicrosporogene sis10apolyplo id10areproductive mode1 aTakamiya, M.1 aWatanabe, M.1 aOno, K.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-0030475989&partnerID=40&md5=996182a1723b75d447e3a2137006f7bd01127nas a2200145   4500008004100000245010200041210006900143260001200212300001400224490000700238520058400245100001800829700001800847856011600865       1996                        eng d00aThe status, distribution, and identification of Georgia Quillwort (Isoetes georgiana; Isoetaceae)0 astatus distribution and identification of Georgia Quillwort Isoe  c1996///  a105 - 1130 v863 aAlthough recently described from only a single population, Isoetes georgiana is now known in at least 12 additional locations on the Georgia coastal plain. The distribution and habitat characteristics of these populations are described. Field and SEM examinations are employed to provide elaboration of the limited morphological and ecological information published to date. Speculation on the probable allopolypoid origin of Isoetes georgiana also is offered. It remains a locally distributed and rare species which may qualify for listing under the U.S. Endangered Species Act.1 aBrunton, D.F.1 aBritton, D.M.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-0347105301&partnerID=40&md5=6d316f38d99032ba8a03e94d7d877dd902130nas a2200241   4500008004100000245014400041210006900185260001200254300001400266490000800280520133600288653001301624653001201637653001401649653001501663653001501678653001501693100001701708700001701725700001801742700001201760856011601772       1996                        eng d00aBiosystematic studies on the genus Isoetes (Isoetaceae) in Japan. III. Variability within qualitative and quantitative morphology of spores0 aBiosystematic studies on the genus Isoetes Isoetaceae in Japan I  c1996///  a281 - 2960 v1093 aQualitative and quantitative characteristics of mega- and microspores from all the cytotypes of Japanese Isoetes are described based on the voucher specimens whose chromosome numbers were known. In I. japonica, the hexaploid possessed reticulate megaspores and levigate microspores, while the octaploid and the heptaploid had echinate microspores. Mega- and microspores of the hexaploid and the octaploid were of normal appearance, while those of the heptaploid displayed polymorphism. The tetraploid and the hexaploid of I. sinensis resembled each other, since they both possessed cristate megaspores and echinate microspores. Echinate megaspores and levigate microspores characterized the diploid I. asiatica. The spore size was largely variable within each cytotype, while the size of the megaspores varied more than that of the microspores. The microspore length was closely correlated with polyploid level. In I. sinensis, the mean microspore length of the tetraploid was 27.6 μm while that of the hexaploid was 31.9 μm, hence these two cytotypes were easily distinguishable. In the hexaploid I. japonica, variations in mega- and microspore size displayed geoclinal variation showing a positive correlation (r=0.43-0.55) with the longitude and the latitude of the populations. A palynotogical key for cytotypes is presented.10aCytotype10aIsoetes10aMegaspore10aMicrospore10aPalynology10aPolyploidy1 aWatanabe, M.1 aTakamiya, M.1 aMatsusaka, T.1 aOno, K.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-0030495119&partnerID=40&md5=def6cedc48f4ad43b95e6e4eb0cbc75e01570nas a2200217   4500008004100000245008700041210006900128260001200197300001200209490000700221520087200228653001101100653002801111653001001139653001101149653001301160653002901173100001401202700002001216856011601236       1996                        eng d00aThe effect of increased water level on Isoetes lacustris L. in Lake Baciver, Spain0 aeffect of increased water level on Isoetes lacustris L in Lake B  c1996///  a57 - 590 v343 aTen months after flooding lake Baciver, water levels were 5.5 m higher than the previous normal and the area formally occupied by the Isoetes population was reduced. All Isoetes originally present below 0.6 m died, and only plants standing between 5.8 and 6.1 m (new depth) survived. As irradiance decreased, remaining individuals produced fewer leaves, but their biomass production was higher, as leaf length increased in response to the diminished available irradiance. Because leaf mortality was excessive, regeneration capacity, population performance and dynamics were adversely affected. In 1992, no new production occurred in Isoetes lacustris individuals surviving after the winter. We suggest that low surface oxygen levels at the water column under the ice, and total anoxia below 6 m depth, caused the demise of the I. lacustris population in Lake Baciver.10aAnoxia10aLeaf primary production10aLight10aOxygen10aPyrenees10aWater level fluctuations1 aGacia, E.1 aBallesteros, E.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-0030188498&partnerID=40&md5=76a5af33fa658c06abddf82d836c45a501481nas a2200157   4500008004100000245006900041210006500110260001200175300001400187490000700201520094400208100001801152700001801170700001901188856011601207       1996                        eng d00aTaxonomy, identity, and status of Isoetes virginica (Isoetaceae)0 aTaxonomy identity and status of Isoetes virginica Isoetaceae  c1996///  a145 - 1600 v613 aThe quillwort Isoetes virginica was described from material from a single location in west central Virginia in 1937. Subsequent treatments have considered it to be either a rare Virginia endemic, a synonym of Isoetes melanopoda or as a broadly defined taxon including the Piedmont endemic Isoetes piedmontana. The discovery of a new population near the type locality and rediscovery of an historical station has permitted cytological and ecological investigations of the original species concept. These investigations establish that Isoetes virginica is tetraploid and provide additional morphological and ecological evidence for this distinct species. Characteristics separating Isoetes virginica from the morphologically similar Isoetes piedmontana and Isoetes melanopoda are discussed. A lectotype for Isoetes virginica is designated. This pteridophyte is considered a Virginia endemic with a total known population of about 350 plants.1 aBrunton, D.F.1 aBritton, D.M.1 aWieboldt, T.F.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-0030432806&partnerID=40&md5=41e631047e913bf96b59884bb864340801211nas a2200145   4500008004100000245004800041210004800089260001200137300001200149490000700161520074500168100001800913700001800931856011600949       1996                        eng d00aTaxonomy and Distribution of Isoetes valida0 aTaxonomy and Distribution of Isoetes valida  c1996///  a16 - 250 v863 aIsoetes valida constitutes an earlier valid name for I. caroliniana. This emergent aquatic, diploid quillwort is known from nine states along the Appalachian Mountains and Piedmont, growing in cold streams, mountain woodland ponds and in the saturated organic ooze of springs from central Pennsylvania to northeastern Alabama. It exhibits a distribution similar to several other endemic Appalachian pteridophytes. Disjunct populations are also known from the Coastal Plain of southeastern Alabama and Delaware. Although similar in appearance to I. engelmannii, I. valida is typically distinguished by its raggedly reticulate megaspore ornamentation, its velum covering 50% or more of the unmarked sporangium wall, and spinulose microspores.1 aBrunton, D.F.1 aBritton, D.M.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-0040732154&partnerID=40&md5=5b1ed779661b2512493ef8631acf499800915nas a2200157   4500008004100000245009800041210006900139260001200208300001100220490000700231520035000238100002000588700001500608700001800623856011600641       1996                        eng d00aIsoetes x bruntonii (Isoetes engelmannii x I. hyemalis), a New Hybrid Quillwort from Virginia0 aIsoetes x bruntonii Isoetes engelmannii x I hyemalis a New Hybri  c1996///  a8 - 150 v863 aIsoetes xbruntonii is the hybrid between the diploid I. engelmannii (2n = 22) and the tetraploid I. hyemalis (2n = 44). An apparently sterile triploid (2n = 33), it has megaspore features intermediate between the two parents, but does not exhibit hybrid vigor. Isoetes xbruntonii is frequent at localities in the outer Coastal Plain of Virginia.1 aMusselman, L.J.1 aBray, R.D.1 aKnepper, D.A.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-1542605410&partnerID=40&md5=9808bd7a43d7b9c4a26e1180bb00b3ce01198nas a2200193   4500008004100000245011500041210006900156260001200225300001400237490000700251520052100258653001300779653002000792653001900812653002100831100001800852700001800870856011600888       1996                        eng d00aSpore Morphology and Cytology of Isoetes Azorica (Pteridophyta Isoetaceae) and ITS Affinity with North America0 aSpore Morphology and Cytology of Isoetes Azorica Pteridophyta Is  c1996///  a113 - 1180 v153 aIsoetes azorica is an endemic of shallow, oligotrophic lakes in the Azores Islands. Cytological investigations determine it to be tetraploid (2n=44). Morphological studies indicate that it shares many characteristics with the North American tetraploid I, tuckermanii. The spore morphology of both species is illustrated by SEM and their degree of similarity discussed. The apparently close affinity between these two taxa is consistent with phytogeographic patterns noted with few other pteridophytes of this region.10aCytology10aIsoetes azorica10aPhytogeography10aSpore morphology1 aBritton, D.M.1 aBrunton, D.F.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-1542470773&partnerID=40&md5=3162bdf0c559fb8cc27d38e86e6faeba