Question

How is a coniferophyta microgametophyta different from a magnoliophyta microgametophyta?

Answer 1

Gymnosperms or Non-flowering plants--

In conifers, each microsporophyll contains two microsporngia. Each microsporangium produces hundreds of microspores. These develop into pollen grains Pollen grains are multicellular and make the microgametophyta.

There is one generative cell that produces two sperms and a tube cell that produces the pollen tube. There are some additional cells but these do not contribute directly to the reproductive process.

The mature gametophyte develops a pollen tube which delivers the male gamete to the archegonia . At this time the sperms are released and fertilisation occurs.

Thus , the microgametophyta in conifers has an endosporic development and an exosphoric development phase. It is protected by a thick wall and it also has wing like projections which carry it for pollination. Once it enters the micropyle, the microgametophyte is also protected by the ovule. But still, to ensure successfull pollination, thousands and thousands of pollen grains are produced.

Angiosperms or Flowering plants--

Magnolia is a flowering plant so it has well developed reproductive parts in its flowers.

The male gametophyta or microgametophyta in magnolia develops in the anther of the flower. The sporogenous tissue , called pollen mother cell, divide meiotically to a cluster of 4 cells called microspore tetrad. On maturity, the anther dehydrates and the microspore separated to form pollen grains. a mature pollen grain contains only one generative cell or male gamete [ unlike conifers whose pollen grain containstwo male gametes] . The other cell is generative. As in conifers, the pollen is covered with a hard wall called exine but this hard cover has a tiny pore called the germ pore from where the pollen tube develops after pollination. The microgamete or sperm moves through this pollen tube to reach the egg within the ovule.

The process of fertilization in angiosperms follows a complicated process which has been termed as 'double fertilization '.

The pollens in magnolia will not have any additional appendage to facilitate pollination as in conifers and also the former will contain two male gametes as compared to only one in magnolia.