Kingdom Plantae AP Biology
Evolutionary History • Chlorophytes gave rise to bryophytes. • Bryophytes gave rise to seedless vascular plants. • Seedless vascular plants gave rise to gymnosperms. • Gymnosperms gave rise to angiosperms.
Major Adaptations • The following adaptations made plants successful on land: • Development of a cuticle • Development of gametangia • Development of vascular tissue • Development of seeds • Development of flowers
What is a gametangia? • A reproductive structure found in some plants in which gametes are formed. • This structure keeps the gametes from drying out. • Types • Anteridium – produces flagellated sperm • Archegonium – produces one egg • Fertilization takes place within the Archegonium.
What is a cuticle? • A cuticle is a waxy covering that prevents water loss. • This made survival on land possible.
What is vascular tissue? • Vascular tissue is made it possible for plants to live on land and away from damp moist areas. • First seen in the seedless vascular plants. • Consists of two types of tissue • Xylem – transports water throughout the plant • Phloem- transports sugar and nutrients to various plant structures
What are seeds? • A package that contains an embryo along with a store of food for the embryo.
What are flowers? • A flower is the reproductive structure of angiosperms.
Major Evolutionary Trends Seen in Plants • Dominant gametophyte generation -> dominant sporophyte generation • Nonvascular -> vascular • Seedless -> seeds • Motile sperm -> pollen • Naked seeds -> seeds in flowers
Major Plant Groups • The major plant groups are: • Bryophytes • Seedless Vascular Plants • Gymnosperms • Angiosperms
Bryophytes • First land plants to evolve from chlorophytes. • Includes mosses, liverworts and hornworts. • Possess two evolutionary adaptations: • A waxy cuticle • Packaging of gametes in gametangia • Lack vascular tissue nonvascular plants • Must live in damp areas
Mosses • Haploid gametophyte is the dominant generation. • Moss sporophyte is tiny, short-lived and dependent on the gametophyte generation for nutrition.
Liverworts • Can reproduce asexually in addition to using alternation of generations.
Seedless Vascular Plants Two major evolutionary changes occurred that allowed the transition from bryophytes: • Switch from gametophyte to sporophyte as dominant generation. • Development of branched sporophytes • First plants to possess vascular tissue. • Includes ferns
Homosporous vs. Heterosporous • Homosporous plants produce a single spore type that gives rise to bisexual gametophytes. • Heterosporous plants produce two types of spores. • Microspores – yield male gametophytes • Megaspores – yield female gametophytes
Ferns • Homosporous plants • Sporophyte is the dominant generation • Spores found on the underside of fern leaves.
Gymnosperms • Major evolutionary changes that occurred between seedless vascular plants and gymnosperms: • Further decline in the prominence of the gametophyte generation in the life cycle • The birth of pollination • The evolution of the seed
Gymnosperms • Heterosporous • Most utilize pollen as a means to transport sperm cells • Gymnosperm literally means “naked seed”. • Includes conifers. • Reproductive structure is a cone • Survive well in dry conditions • Keep leaves year round
Angiosperms • Angiosperm literally means “vesseled seed” • Two major classes • Monocots • Dicots • Xylem has been adapted from that of a gymnosperm. • Gymnosperm xylem made of tracheid cells • Angiosperm xylem made of vessel elements
Angiosperms • Utilize the flower for reproduction.
Flower Important Parts of a Flower • Stamen – male structure • Anther – produces pollen • Filament – stalk that supports anther • Carpel – female structure • Stigma – sticky; receiver of pollen • Style – pathway leading to the ovary • Ovary – Contains the eggs; will ripen to become fruit • Petal – colorful portion of flower that attracts pollinators