Question

What is the significance of heterospory?

Answer 1

Hint: Heterospory refers to the formation of two different types of spores with different sizes. Male microspores are smaller than female megaspores. Microsporangia and megasporangia are produced by meiosis in the spore mother cells in the sporophyte stage of the plant, which yield haploid microspores and megaspores, respectively. The microspore germinates and develops into a male gametophyte, whereas the megaspore becomes a female gametophyte. Female gametophytes have archegonia, while male gametophytes have antheridia.
Pinus, Cycas, and other Gymnosperms are heterosporous. The majority of Pteridophytes are homosporous, however some taxa, such as Selaginella and Salvinia, are heterosporous.

Complete answer:
Significance of heterospory -
In heterosporous forms, gametophyte development is endosporic, meaning that the sporophyte feeds the developing gametophyte. As a result, gametophyte growth in independently growing gametophytes is unaffected by environmental factors.
It expresses the ability of plants to determine their sex. A microspore, for example, always generates a male gametophyte, while a megaspore always creates a female gametophyte.
Even after conception, the parent retains megaspores, which ensure that the developing embryo receives nutrients.
While the megaspore is still inside the megasporangium, the female gametophyte begins to develop.
The female gametophyte's reliance on the sporophyte for nutrition is a better starting point for the formation of new embryos than an independent green prothallus that must provide its own sustenance.

Note:
The majority of Pteridophytes produce spores that are identical. Homosporous Pteridophytes and homospory are terms used to describe this phenomenon. There are, however, some Pteridophytes that produce two types of spores (differing in size, structure and function).
Pteridophytes that are heterosporous are known as heterospory, and the phenomenon is called heterospory. Microspores and megaspores are the two forms of spores. Microspores are smaller and form the male gametophyte, whilst megaspores are larger and form the female gametophyte.