What is a plant's lifecycle?

Answer 1

Depends on the plant:

If it is a bryophyte, most of the time is spent in the gametophyte stage, until a sperm and egg fertilize. Once that happens the plant goes to the sporophyte stage, where spores are released to create more gametophytes.

In seedless vascular plants, such as ferns, the plant still starts in the gametophyte (until fertilization) but the majority of the cycle is spent in the sporophyte stage (release spores to create new gametophytes).

Seed bearing vascular plants have both stages at the same time but the sporophyte stage is not seen, all takes place in the flower.