As we will see in the following lessons, the generation in which the plant spends most of
its lifecycle differs between various plants. In the plants that first evolved, the gametophyte
takes up the majority of the lifecycle of the plant. During the course of evolution, the
sporophyte became the major stage of the lifecycle of the plant. In flowering plants, the
female gametophyte is retained within the sporophyte and the male gametophyte is the
pollen.
Figure 10.5: In ferns, the sporophyte is dominant and produces spores that germinate into
a gametophyte; after fertilization the sporophyte is produced. Ferns will be discussed in
further detail in the next lesson. ( 2 )
Classification of Plants
The Plant Kingdom is formally divided into 12 phyla, and these phyla are subdivided into
four groups:
- nonvascular plants
- seedless vascular plants
- nonflowering plants
- flowering plants
Portrayed inFigure10.6are some of the rich diversity of this kingdom. These four groups
are based on the evolutionary history of significant features in plants. The first significant
featuretoevolveinthePlantKingdom, aftertheretentionoftheembryo, wasvasculartissue.
Vascular tissue allowed the transport of water and food throughout the plant. The phyla
that were around before the evolution of the vascular tissue are known as thenonvascular
plants(withoutvasculartissuetomovewater, nutrientsandfood). Thenextsignificantstep