How does a fertilized egg become a new lower vascular plant sporophyte?

In lower vascular plants, the transition from a fertilized egg to a new sporophyte occurs through a process of continuous development rather than the formation of a dormant seed.1

Following fertilization, where a sperm cell fuses with an egg within the archegonium, the resulting zygote contains a full set of chromosomes from each parent. The development process proceeds as follows:2

• Cleavage: The zygote undergoes cell division, splitting into daughter cells that establish the primary polarity of the embryo.3
• Embryo Formation: Through rapid division, these cells differentiate into the essential organs of the young sporophyte: the primary root, the first leaf, and the stem apex. Temporary structures, such as a foot, may also form to assist in nutrient absorption from the gametophyte.23
• Establishment: Unlike seed plants, the embryo does not enter a dormant state. It remains dependent on the parental gametophyte until it develops sufficiently to become a physiologically independent plant. As the young sporophyte establishes itself, the gametophyte eventually dies.14