Question

Heterosporous pteridophytes (e.g., Selaginella) always produce the gametophytes?
(a) Monoecious
(b) Dioecious
(c) Homothallic
(d) None of the above

Answer 1

Hint: Pteridophytes are also known as the cryptogams because they do not produce any flowers or seeds. The pteridophytes reproduce both by the vegetative and sexual methods and maybe in homozygous or heterozygous conditions.

Complete answer:
Pteridophyta is one of the older groups of plants present in the Plant kingdom. Their evolution has started earlier than that of the angiosperms. They are called the “true” plants that were the first vascular plants but were seedless and show true alternation of generations. They may be in homosporous or heterosporous condition while their body constitutes roots, stems, and leaves.
The spores when are present in homosporous condition (in both male and female parts only one type of gametophyte is present) then the gametophyte produced is called monoecious but when the spores are present in heterozygous condition (male and female parts produce different gametophytes, the male produces microspores while female produces megaspores) then the gametophyte produced is called dioecious.
Selaginella is commonly known as spike moss or small club moss belonging to the order Selaginellales and is a living genus. It is a creeping plant with simple, scale-like leaves having branched stems from where the roots arise. In the lower leaf epidermis, the chloroplast are present inside the spongy layer cells which are discoidal in shape while the plastids present are in the crescent shape. The gametophytes produced in Selaginella are heterozygous containing microspores and megaspores as male and female gametophytes respectively. Thus, Selaginella produces dioecious gametophytes.

So, the correct answer is ‘Dioecious’.

Note:
The sexuality of pteridophytes' gametophytes can be delegated follows:
Dioecious: the individual gametophyte is either a male creating antheridia and sperm or female delivering archegonia and egg cells.
Monoecious: every individual gametophyte may produce both antheridia and archegonia and it can function both as a male also as a female.