Evolution and Diversity of Plants Mader: Biology 8th Ed.

Alternation of Generations Nonvascular Plants Vascular Plants Seedless Outline Evolutionary History Alternation of Generations Nonvascular Plants Vascular Plants Seedless Seed Angiosperms Monocots and Dicots Flowers Mader: Biology 8th Ed.

Evolutionary History of Plants Plants are thought to have evolved from freshwater algae over 500 million years ago. Marked by four evolutionary events associated with four major groups of plants….. Mader: Biology 8th Ed.

Evolutionary History of Plants Nonvascular Plants nourishment of a multicellular embryo within the body of the female plant. Seedless Vascular Plants Advent of vascular tissue. Gymnosperms and Angiosperms Produce seeds. Flowering Plants Attract pollinators that give rise to fruits. Mader: Biology 8th Ed.

Alternation of Generations All plants have a life cycle that includes an alternation of generations. Two multicellular individuals alternate, each producing the other. Sporophyte = diploid generation. Gametophyte = haploid generation. Mader: Biology 8th Ed.

Alternation of Generations Mader: Biology 8th Ed.

Alternation of Generations Mader: Biology 8th Ed.

Alternation of Generations Sporophyte (2n) is named for its production of spores by meiosis. Spore is haploid reproductive cell. Gametophyte (n) is named for its production of gametes. Mader: Biology 8th Ed.

Reduction in Size of Gametophyte Mader: Biology 8th Ed.

Alternation of Generations Appearance of generations varies widely. In ferns, female portions are archegonia and are fertilized by flagellated sperm. In angiosperm, female gametophyte (embryo sac), consists of an ovule. Following fertilization, ovule becomes seed. In seed plants, pollen grains are mature sperm-bearing male gametophytes. Mader: Biology 8th Ed.

Protection of Eggs and Embryos Mader: Biology 8th Ed.

Other Terrestrial Adaptations Vascular tissue transports water and nutrients to the body of the plant. Cuticle is an effective barrier to water loss. Stomata bordered by guard cells that regulate opening, and thus water loss. Mader: Biology 8th Ed.

Leaves of Vascular Plants Mader: Biology 8th Ed.

Do not have true roots, stems, or leaves. Nonvascular Plants Do not have true roots, stems, or leaves. Gametophyte is dominant generation. Produces eggs in archegonia and flagellated sperm in antheridia. Sperm swim to egg in film of water. Mader: Biology 8th Ed.

Nonvascular Plants Hornworts (phylum Anthocerophyta) have small sporophytes that carry on photosynthesis. Mader: Biology 8th Ed.

Nonvascular Plants Liverworts (phylum Hepatophyta) have either flattened thallus or leafy appearance. Mader: Biology 8th Ed.

Can reproduce asexually by fragmentation. Nonvascular Plants Mosses (phylum Bryophyta) usually have a leafy shoot, although some are secondarily flattened. Can reproduce asexually by fragmentation. Dependent sporophyte consists of foot, stalk, and sporangium. Mader: Biology 8th Ed.

Moss Life Cycle Mader: Biology 8th Ed.

Xylem conducts water and dissolved minerals up from roots. Vascular Plants Xylem conducts water and dissolved minerals up from roots. Phloem conducts sucrose and other organic compounds throughout the plant. Lignin strengthens walls of conducting cells in xylem. Mader: Biology 8th Ed.

Vascular Tissue Mader: Biology 8th Ed.

Seedless Vascular Plants Club Mosses (phylum Lycophyta) Typically, branching rhizome sends up short aerial stems. Leaves are microphylls (have only one strand of vascular tissue). Sporangia occur on surfaces of sporophylls. Grouped into club-shaped strobili. Mader: Biology 8th Ed.

Club Mosses Mader: Biology 8th Ed.

Seedless Vascular Plants Ferns and Allies Horsetails (phylum Sphenophyta) Rhizome produces tall aerial stems. Contains whorls of slender, green branches. Small, scalelike leaves also form whorls at the joints. Mader: Biology 8th Ed.

Horsetail Mader: Biology 8th Ed.

Whisk Ferns (phylum Psilotophyta) Branched rhizome has rhizoids. Mutualistic mycorrhizal fungus helps gather nutrients. Ferns (phylum Pterophyta) Large conspicuous fronds. Divided into leaflets. Dominant sporophyte produces windblown spores. Mader: Biology 8th Ed.

Whisk Ferns and Ferns Mader: Biology 8th Ed.

Fern Life Cycle Mader: Biology 8th Ed.

Fern Life Cycle Mader: Biology 8th Ed.

Seed plants are the most plentiful plants in the biosphere. Seed coat and stored food allow an embryo to survive harsh conditions during long period of dormancy. Heterosporous Drought-resistant pollen grains. Ovule develops into seed. Mader: Biology 8th Ed.

Gymnosperms (naked seeds) Gymnosperms have ovules and seeds exposed on the surface of sporophylls. Mader: Biology 8th Ed.

Conifers, as well as other gymnosperm phyla, bear cones. Tough, needlelike leaves of pines conserve water with a thick cuticle and recessed stomata. Considered a “soft” wood because it consists primarily of xylem tissue. Mader: Biology 8th Ed.

Conifers Mader: Biology 8th Ed.

Pine Life Cycle Mader: Biology 8th Ed.

Pine Life Cycle Mader: Biology 8th Ed.

Pollen and seed cones on separate plants Cycads Cycads (phylum Cycadophyta) have large, finely divided leaves that grow in clusters at the top of the stem. Oldest of the gymnosperms (about 320 million years ago) Pollen and seed cones on separate plants Mader: Biology 8th Ed.

Ginkgoes (phylum Ginkgophyta) are dioecious (male and female plants) with some trees producing seeds and others producing pollen. One surviving species =Gingko biloba Mader: Biology 8th Ed.

Gnetophytes (phylum Gnetophyta) believed to be closest to angiosperms because of similarity in xylem tissue and some even produce nectar for pollinators! Mader: Biology 8th Ed.

Angiosperms (covered seeds) Angiosperms (phylum Anthophyta) are an exceptionally large and successful group of plants. Produce flowers Seeds are enclosed in a fruit. Oldest fossils are 130 million years old Mader: Biology 8th Ed.

Two classes of flowering plants. Monocotyledones (Monocots) Monocots and Eudicots Two classes of flowering plants. Monocotyledones (Monocots) One cotyledon in seed. Eudicotyledones (Dicots) Two cotyledons in seed. Mader: Biology 8th Ed.

Penducle (flower stalk) expands at tip into a receptacle. The Flower Penducle (flower stalk) expands at tip into a receptacle. Bears sepals, petals, stamens, and carpels, all attached to receptacle in whorls. Calyx (collection of sepals) protect flower bud before it opens. Corolla (collection of petals). Mader: Biology 8th Ed.

Each stamen consists of an anther and a filament (stalk). The Flower Each stamen consists of an anther and a filament (stalk). Carpel has three major regions. Ovary - Swollen base. Fruit Style - Elevates stigma. Stigma - Sticky receptor of pollen grains. Mader: Biology 8th Ed.

Mader: Biology 8th Ed.

Flowering Plant Life Cycle Mader: Biology 8th Ed.

Flowering Plant Life Cycle Mader: Biology 8th Ed.

Flowers and Diversification Wind-pollinated flowers are usually not showy. Bird-pollinated flowers are often colorful. Night-blooming flowers attract nocturnal mammals or insects. Usually white or cream-colored. Fruits of flowers protect and aid in dispersal. Utilize wind, gravity, water, and animals for dispersal. Mader: Biology 8th Ed.