02457nas a2200121   4500008004100000245006400041210006300105300001000168490000700178520201700185100001602202856011702218       2014                        eng d00aHeterosporangium: A new category of sporangium in Lycopsida0 aHeterosporangium A new category of sporangium in Lycopsida  a77-920 v563 aThis is being hypothesised that the heterospory to begin with, might have originated within one specific sporangium thereafter separate male and female sporangia would have evolved in due course of time. This new category of a sporangium, is hereby named as "heterosporangium", conceived to have been the cradle sporangium for the origin of heterospory. Such a sporangium may have possessed three types of spores, viz. microspores, megaspores and morphologically distinct spores possessing resemblances with spores of past lineages/fossils. Such a classical structure has been exemplified by a fundamental discovery of "intrasporangial heterospory" in 1968. This appears that this evolutionary phase could have followed the path of sequential evolution of isosporangium-anisosporangium-heterosporangium and finally, leading to "intersporangial heterospory" in the form of independent microsporangium and megasporangium. The independent sex differentiated sporangia must have had evolved by selective degeneration of spore mother cells in a differentiating young heterosporangium. In other words, a microsporangium should have evolved by the degeneration of megaspore mother cells and megasporangium by early degeneration of microspore mother cells. This selective degeneration must have been operative on account of some genetic mechanism as suggested by Bell in 1996 and later, demonstrated by our observations on epigenetic mechanisms suspecting mainly abrupt hypomethylation of DNA, to be responsible event as indicated in heterosporangia of Isoetes pantii Goswami et Arya. This paper exclusively establishes heterosporangium as a structure of rare evolutionary importance genetically inherent within the genome of the species observed consistently for more than five decades. Recent decline of such plants of I. × pantii does not lower down importance of heterosporangium because its physical presence can never be denied. The future of a species or an organ depends on operative modes of natural selection.1 aGoswami, H.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-84897648217&partnerID=40&md5=b534f6c64ae2778a73ed5149a525d6b501347nas a2200193   4500008004100000245013900041210006900180260001200249300001400261490000700275520061600282653002000898653003400918653002600952653001900978653002300997100001601020856011701036       2012                        eng d00aDirectional selection of bisexual plants in natural populations of Isoetes pantii (Pteridophyta: Isoetaceae) with chromosome evolution0 aDirectional selection of bisexual plants in natural populations   c2012///  a103 - 1150 v543 aPopulation biology studies during 1966-2010 have revealed that the proportion of bisexual plants has declined in natural populations of Isoetes pantii at Narsinghgarh (Central India), where it has been growing with the parental species I. coromandelina L. and I. sampathkumaranii Rao. Since many fundamental discoveries have been observed from within the microsporangia (male sporangia) over four decades the decline of production of male sporangia by this species has been briefly presented in the light of chromosomal as well as ecological factors. Directional selection appears to have favoured this decline.10abisexual plants10adifferential sexual selection10adirectional selection10aIsoetes pantii10anatural population1 aGoswami, H.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-84859148941&partnerID=40&md5=ca2f20773a816d764eafa178c18cb50a