Question

Female ovule of magasporophyll of cyc

Answer 1

Life Cycle of Cycas: Vegetative and Sexual Life Cycle

[I] Vegetative Cycle:

• This is a deviation of regular alternation of generations between sporophyte and gametophyte.

• In this type of cycle, a sporophyte gives rise to a sporophyte of the same sex. Vegetative Cycle takes place with the formation of adventitious buds called bulbils in the basal part of stem (

• Bulbils are protected by scale leaves. During favourable period bulbils detach from the parent and grow into an independent sporophyte.

• This cycle is more prevalent in Northern India where male plants of Cycas revolute are not found.

[II] Sexual cycle (Sexual reproduction):

• The sexual life cycle of Cycas is diplohaplontic. It shows heterologous or heteromorphic type of alternation of generations because the sporophyte (2n) and gametophyte (n) generations exhibit morphological differences. In Cycas, the sporophyte (2n=22) is a complicated, independent and dominant generation whereas the gametophytes (n=ll) are inconspicuous and endosporic. The gametophytes of Cycas are of 2 types: male or microgametophyte and female or magagametophyte.
• Female gametophyte is retained whereas male gametophyte is transfer during pollination.