Botany and Plant Science

In Pteridophyte Dryopteris the gametophytes give rise to sporophyte by gametic union and sporophyte gives rise to gametophyte by forming haploid spores after meiosis. 

Young sporophyte of Pteris draws nourishment from the foot. Foot is formed first, which absorbs water, minerals from prothallus. Prothallium, or prothallus is usually the gametophyte stage in the life of a fern or other pteridophyte. The prothallium develops from a germinating spore. It is a short-lived and inconspicuous heart-shaped structure typically 2-5 millimeters wide, with a number of rhizoids (root-like hairs) growing underneath, and the sex organs: archegonium (female) and antheridium (male). Appearance varies quite a lot between species. Some are green and conduct photosynthesis, while others are colorless and nourish themselves underground as saprotrophs. 

Dryopteris species can be identified by the circular shaped sori, that is covered by a kidney-shaped, translucent tissue. It is called as indusium. It is a shield like outgrowth of the leaves.

Some epidermal cells give rise uniseriate bicellular brown hairs on young leaves of Pteris or any other fern, called as ramenta. 

In the male gametophyte of Selaginella, the single prothallial cell is the only vegetative structure, as the rest of the cells develop into the antheridium.

Dryopteris, is a genus with more than 250 species and is widespread in the temperate zones in northern hemisphere. The diploid sporophyte and haploid gametophyte of Dryopteris regularly alternate with each other. The haploid spore which gives rise to the gametophyte which is the monoecious prothallus and bears sex organs on its ventral side. After fertilization, they give rise to the sporophyte which is the dominant asexual member in the life cycle of the plant and is a perennial evergreen, differentiated into rhizome (stem), roots and leaves. Hence, both the gametophyte and sporophyte are independent of each other.

Dorstenia is a genus in the Moraceae family known for its unique inflorescence called a coenanthium, where the receptacle is fleshy and concave.

Microspores of Selaginella are very small, typically measuring around 15 micrometers in diameter.

In Dryopteris the opening mechanism of sporangium is effectively operated by stomium. Stomium is formed of the thin-walled cells, marking the line or region of dehiscence of a fern sporangium. It is the opening in an anther, usually between lip cells through which dehiscence occurs.

In the stem of Selaginella, the endodermal cells are elongated and form bridge-like structures called trabeculae that connect the stele to the cortex.

In Selaginella, the development of the male gametophyte is endosporic, meaning it occurs entirely within the microspore wall.

The megaspore of Selaginella germinates to produce the female prothallus, which bears the archegonia.

The 13-celled male gametophyte of Selaginella consists of 1 prothallial cell and a 12-celled antheridium.

In Selaginella, the megasporophyll bears the megasporangium, which is functionally analogous to the carpel in angiosperms that encloses the ovule. This comparison highlights the evolutionary trend toward seed-bearing structures.

The male gametophyte of Selaginella is highly reduced. It consists of a single prothallial cell and an antheridium.