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Heterospory is the production of spores of two different sizes and sexes by the sporophytes of land plants. The smaller of these, the microspore , is male and the larger megaspore is female. Heterospory evolved during the Devonian period from isospory independently in several plant groups: the clubmosses , the ferns including the arborescent ...
There is debate as to whether endospory or heterospory evolved first. Some debate centers upon the requirement of endospory to develop before heterospory. [2] Endospory is assumed to follow heterospory but it has been suggested that without endospory, early plant species dependency on water fertilization and environmental impacts on gametophytic gene expression would have reduced the chances ...
The board also owns a stadium in Latifabad used for league, inter-club and -city hockey tournaments. But sporting events The District Hockey Association (DHA) for the Hyderabad District, Pakistan had allocated a budget of 1.6 million rupees for renovations for the betterment of hockey arenas but were reluctant to give the board their share.
Spores of two distinct sizes (heterospory or anisospory): larger megaspores and smaller microspores. When the two kinds of spore are produced in different kinds of sporangia, these are called megasporangia and microsporangia. A megaspore often (but not always) develops at the expense of the other three cells resulting from meiosis, which abort.
[11] Because the Marsileaceae produce two kinds of spore (and thus two kinds of gametophyte), they are called heterosporous. While heterospory is the norm among all plants with seeds, such as the flowering plants and conifers, it is very rare among other groups of plants. Also, most heterosporous plants produce their two kinds of sporangia in ...
In gymnosperms and flowering plants, the megaspore is produced inside the nucellus of the ovule.During megasporogenesis, a diploid precursor cell, the megasporocyte or megaspore mother cell, undergoes meiosis to produce initially four haploid cells (the megaspores). [1]
Pteris platyzomopsis has been known by the synonym Platyzoma microphyllum. [1] The genus Platyzoma has been placed as the only species in family Platyzomataceae. [4] [2] Tryon has speculated that the species, with its incipient heterospory, unusual chromosome number (2n=78) and other features, may represent a stage transitional to the heterosporous aquatic ferns.
Dayaram Jethamal Sindh Government Science College, [1] (Urdu: ڈی جے سندھ گورنمنٹ سائنس کالج) commonly known as DJ Science College, is a public community college that is affiliated with the Board of Intermediate Education Karachi and the University of Karachi — it is located near Burns Road in Karachi, Sindh, Pakistan. [2]