Chapter 30 - Plant diversity II: The evolution of seed plants. This chapter explain why pollen grains were an important adaptation for successful reproduction on land; list the four phyla of gymnosperms; describe the life history of a pine; indicate which structures are part of the gametophyte generation and which are part of the sporophyte generation;. | Chapter 30 Plant Diversity II: The Evolution of Seed Plants Overview: Transforming the World Seeds changed the course of plant evolution, enabling their bearers to become the dominant producers in most terrestrial ecosystems. A seed consists of an embryo and nutrients surrounded by a protective coat. The gametophytes of seed plants develop within the walls of spores that are retained within tissues of the parent sporophyte. What human reproductive organ is functionally similar to this seed? Figure What human reproductive organ is functionally similar to this seed? Seeds and pollen grains are key adaptations for life on land In addition to seeds, the following are common to all seed plants: Reduced gametophytes Heterospory Ovules Pollen Gametophyte / sporophyte relationships in different plant groups Reduced (usually microscopic), dependent on surrounding sporophyte tissue for nutrition Reduced, independent (photosynthetic and free-living) Gametophyte Sporophyte (2n) Sporophyte (2n) Gametophyte (n) Sporophyte Example Gametophyte (n) Dominant Dominant Dominant Reduced, dependent on gametophyte for nutrition Mosses and other nonvascular plants Ferns and other seedless vascular plants Seed plants (gymnosperms and angiosperms) PLANT GROUP Gymnosperm Angiosperm Microscopic female gametophytes (n) inside ovulate cone Microscopic male gametophytes (n) inside pollen cone Sporophyte (2n) Sporophyte (2n) Microscopic female gametophytes (n) inside these parts of flowers Microscopic male gametophytes (n) inside these parts of flowers Figure Gametophyte/sporophyte relationships in different plant groups Heterospory: The Rule Among Seed Plants The ancestors of seed plants were likely homosporous, while seed plants are heterosporous. Megasporangia produce megaspores that give rise to female gametophytes. Microsporangia produce microspores that give rise to male gametophytes. Ovules and Production of Eggs An ovule consists of a megasporangium, megaspore, and one | Chapter 30 Plant Diversity II: The Evolution of Seed Plants Overview: Transforming the World Seeds changed the course of plant evolution, enabling their bearers to become the dominant producers in most terrestrial ecosystems. A seed consists of an embryo and nutrients surrounded by a protective coat. The gametophytes of seed plants develop within the walls of spores that are retained within tissues of the parent sporophyte. What human reproductive organ is functionally similar to this seed? Figure What human reproductive organ is functionally similar to this seed? Seeds and pollen grains are key adaptations for life on land In addition to seeds, the following are common to all seed plants: Reduced gametophytes Heterospory Ovules Pollen Gametophyte / sporophyte relationships in different plant groups Reduced (usually microscopic), dependent on surrounding sporophyte tissue for nutrition Reduced, independent (photosynthetic and free-living) Gametophyte Sporophyte (2n) .
