(B) Anthophyta - the flowering plants

    With over 250, 000 species, flowering plants are the most diverse extant plant group. The sporophyte stages of flowering plants are extremely variable in form, ranging in size from trees over 100m tall in Eucalyptus to tiny, few-celled aquatic duckweeds (Lemna sp.), and include such varied habits as trees, shrubs, succulents, vines, and herbs. Because they are also seed plants, as in the gymnosperms, the megagametophyte in Anthophyta is reduced and retained in the megasporangium (nucellus).

  Anthophyta is characterized by the enclosure of the ovules within carpels to form an ovary, or pistil, as well as by other synapomorphies involving reproductive attributes and the structure of the vascular tissues, and, of course, by the production of elaborate strobili called flowers. The flowering plants include two main classes: the monocotyledons (monocots) and the dicotyledons (dicots). Similar in many aspects, they represent separate evolutionary lines with recognizeable differences.
 

    The first flowering plants to evolve were dicots. This group includes most flowering trees and shrubs, as well as herbaceous plants. The monocots evolved later, and are a monophyletic group derived from within the dicot lineage. Monocots include familiar plants like grasses, lilies, orchids, cattails, and palms.

• Compare the diversity of the Anthophyta with that seen in other groups.
• What characteristics seem to unify this group?