Name three groups of plants that bear archegonia. Briefly describe the life cycle of any one of them.
Three groups of plants that bear archegonia are given below:
The life cycle of a pteridophyte, then it consists of two morphologically distinct phases:
(i) The gametophytic phase
(ii) The sporophytic phase.
These two phases come one after another in the life cycle of a pteridophyte and this phenomenon is called alternation of generation. The gametophyte is haploid with a single set of chromosomes. It produces male sex organs antheridia and female sex organs archegonia.
(i) The antheridia may be embedded or projecting type. Each antheridium has a single-layered sterile jacket enclosing a mass of astrocytes.
(ii) The androcytes are flask-shaped, sessile or shortly stalked and differentiated into globular venter and tubular neck.
(iii) The diploid zygote is the first cell of the sporophytic generation. It is retained inside the archegonium and forms the embryo.
(iv) The antherozoids after liberation from antheridium reach up to the archegonium fuses with the egg and form a diploid structure known as zygotes.
(v) The archegonium contains a large egg, which is non-motile.