Botany and Plant Science

The megaspores and microspores germinate and give rise to female and male gametophytes, respectively. The female gametophytes in these plants are retained on the parent sporophytes for variable periods. The development of the zygotes into young embryos take place within the female gametophytes. 

The four megaspores derived from a megaspore mother cell may not always be functional. i.e. In S.rupestris single megaspore is functional.

The retention of the megaspore and the development of the embryo within the female gametophyte, which remains attached to the parent sporophyte, is a crucial evolutionary step toward the seed habit.

In Dryopteris, on the lowerside of the leaflet an outgrowth is present. It consists of a stalk like placenta and a flap, that protects group of sporangia. This is called as true indusium.

In Dryopteris, the annulus and the stomium help in the dehiscence of the sporangium and dispersal of spores. At maturity, the sporangium dehisces by drying action, which exerts pressure on mouth assisted by shrinkage of the annulus. Lastly mouth of sporangium open and spores are liberated.

The antheridium (male organ) is located on the lower surface of the fern prothallus and the archegonium (female organ) is located on the upper surface of the fern prothallus.

Cryptogams are plants, that reproduce by spores without flowers or seeds but angiosperms possess flowers and seeds. Angiosperms are more advanced than the gymnosperms. They consist of covered seeds as compared to the naked seeds of the gymnosperms. Angiosperms bear true fruits. They show characteristics of double fertilization.

The spermatophyta comprises of all those land plants that produce flowers and seed. In angiosperms, and other seed plants, gametophytes are not independent seed plants, instead they are small structures found embedded within the sporophyte.

Stele can be defined as the central core of the stem and root of a vascular plant, consisting of the vascular tissue (xylem and phloem) and associated supporting tissue. 

Sporocarp is a reproductive structure of some aquatic ferns like Marsilea. Sporocarps are functionally and developmentally modified leafwhich bears several sori. Each sori consists of sporangia of two types -mega sporangia producing simple large female megaspore and microsporangia producing many small male microspore.

The mature male gametophyte of Selaginella consists of 13 cells: 1 prothallial cell and 12 cells forming the antheridium (4 jacket cells, 4 primary androgonial cells, and 4 androcytes).

The heart-shaped prothallus is the characteristic feature of ferns and mainly belong to Polypodiaceae. They show polarity and dorsoventrally. The prothallus contains both the antheridia and archegonia which are embedded in the prothallus. Since it forms the male and female gametes the prothallus -is considered as the gametophyte.

Equisetum is characterized by its distinct jointed, ribbed, and green stems, which are capable of photosynthesis.

In the life cycle of pteridophytes, the sporophyte is diploid and produces spores through meiosis within the sporangia.

Circinate vernation is characteristic feature of division filicophyta  (e.g.,Dryopteris) while Selaginella include in division lycophyta.