These are plants belonging to the group Bryophyta, which contains all plants without a vascular system.
The predominant stage of the life cycle of a moss is the gametophyte which consists of two stages.
The first stage is the protonema stage and the second stage is the leafy stage.
The zygote develops into an embryo soon after fertilization which differentiates into the seta, foot, and sporangium.
The foot seeps through the center, into the gametophyte stem wherein the transfer cells move nutrients and water from gametophyte to dependent sporophytes.
Seta rapidly elongates, advancing the soon-to-be-formed sporangium above the top of leafy gametophytes.
The archegonium increases as sporophytes enlarge. Now it is known as the calyptra.