Question

Name three groups of plants that bear archegonia. Briefly describe the life cycle of any one of them?

Answer 1

Hint: The first group of plants that bear archegonia are called the amphibians of the plant kingdom. The second group of plants are popularly used for medicinal purposes and also serve as soil binders. The third group of plants are the one in which the ovary is not enclosed by an ovary wall and so remains exposed.

Complete answer:
The three groups of plants that bear archegonia are bryophytes including mosses and liverworts, pteridophytes which include horsetails and ferns, and gymnosperms.
Let's study the life cycle of moss by beginning with their vegetative reproduction.
The predominant stage in the life cycle of a moss is the gametophyte which in turn consists of two stages. The first stage is known as the protonema stage. It develops directly from spore. Protonema is a green, creeping but branched and frequently filamentous stage. The second stage is named as the leafy stage. It develops as a lateral bud from the secondary protonema. This stage exhibits upright slender axes bearing spirally arranged leaves. This spiral of leaves is attached to the soil through branched and multicellular rhizoids. This is also the stage which bears sex organs. Vegetative reproduction in mosses occurs by fragmentation and budding in the secondary protonema.
Now let's briefly learn about their sexual reproduction.
In this phase, the sex organs antheridia and archegonia are formed at the apex of the leafy shoots. Post fertilization the zygote transforms into a sporophyte which consists of a foot, seta and capsule. The capsule is filled with spores. These spores are formed as a result of meiosis. There is an elaborate mechanism in place for spore dispersal in mosses.
So, the correct answer is, ‘Bryophytes, pteridophytes and gymnosperms.’

Note:
- Mosses have more elaborate sporophyte than liverworts. Some common examples of mosses are Funaria, Polytrichum and Sphagnum.
- Archegonia in pteridophytes possesses eggs. The male gametes from the antheridia are released directly to the mouth of the archegonium.
- In gymnosperm, male gametes are carried in a pollen tube towards the archegonia in the ovules.