Question

What do you understand by the term ‘naked embryo’? Name any two divisions of the kingdom – plantae that have naked embryos. Give an example of each division.

Answer 1

Fertilization in plants leads to the formation of an embryo. Embryogenesis, that is the formation of the ovule, consists of two distinct structures – the embryo and the endosperm. This leads to the development of the seed. Embryos are multicellular structures of undifferentiated cells. It consists of a bipolar axis and cotyledons.

Complete answer:
Spores are also called naked embryos. These embryos are formed after fertilization but are not found inside the integuments of seeds. In the plant kingdom, two divisions form naked embryos. These are Bryophyta and Pteridophyta. Sori are clusters of sporangia that produce spores. These are found in ferns (Pteridophytes and fungi. Examples of plants that contain naked embryos are Marsilea and Funaria.

Additional information:
Bryophytes:
Bryophytes are nonvascular plants belonging to three divisions: the liverworts, hornworts, and mosses. These plants are found at diverse habitats through a wide range of temperature, moisture, and from sea-level to alpine levels. Thus, it can grow at places where even vascularized plants cannot grow like rocks and bare soil because it does not depend on roots for the uptake of nutrients. The life cycle of Bryophyte has alternations of generations like any other embryophyte. The two stages in the life cycle are sporophyte and gametophyte. Out of which the gametophyte stage is dominant in Bryophytes.
Pteridophytes:
These are spore-forming vascular plants having alternations of generation. The sporophyte is well-differentiated into roots, stems, and leaves. Pteridophytes have an adventitious root system.

Note: Embryogenesis is followed by other stages of the life cycle like dormancy and germination. The zygote produced after fertilization undergoes multiple cellular divisions and differentiation steps to form a mature embryo. It consists of shooting apical meristem, hypocotyl, root meristem, root cap, and cotyledons. Cellular differentiation leads to the development of the root-shoot body and the formation of primary tissue layers.