Chapter 22 Plant Evolution and Classification

Evolution The oldest plant fossils are 400 million years old. The oldest plant fossils are 400 million years old. Many plants that grew during the carboniferous period (280 mya) provide us with our fossil fuels. Many plants that grew during the carboniferous period (280 mya) provide us with our fossil fuels. Adaptations enabled plants to live on land. Adaptations enabled plants to live on land.

Adaptations for Land Survival Cuticle: waxy protective covering Cuticle: waxy protective covering Multicellular gametangia: structures that protect gametes during development Multicellular gametangia: structures that protect gametes during development Vascular Tissue: complex tissues that transport water and food and help support the weight of the plant (roots, stems, leaves) Vascular Tissue: complex tissues that transport water and food and help support the weight of the plant (roots, stems, leaves) Spores: resistant reproductive cells (ferns) Spores: resistant reproductive cells (ferns) Seeds: protect and nourish embryo (gymno- and angiosperms) Seeds: protect and nourish embryo (gymno- and angiosperms)

Reproduction Alternation of Generations Plants and Algae undergo this life cycle. Plants and Algae undergo this life cycle. Gametophyte: haploid multicellular structure that produces gametes. Gametophyte: haploid multicellular structure that produces gametes. Sporophyte: developed from the zygote; produces sporangia which in turn form the gametophyte structure. Sporophyte: developed from the zygote; produces sporangia which in turn form the gametophyte structure.

Nonvascular Plants

Have no true roots, stems or leaves Have no true roots, stems or leaves Examples are mosses, liverworts Examples are mosses, liverworts and hornworts (Division Bryophyta) Description Description Lie close to the ground to absorb water Lie close to the ground to absorb water Gametophyte is the obvious carpet-like structure Gametophyte is the obvious carpet-like structure Rhizoids are root-like structures that act as anchors Rhizoids are root-like structures that act as anchors Sporophyte is the stalk-like structure that produces spores Sporophyte is the stalk-like structure that produces spores

Ecology of Mosses Rhizoids help prevent erosion. Rhizoids help prevent erosion. Mosses are often pioneer species in the development of new biological communities. Mosses are often pioneer species in the development of new biological communities. The Sphagnum moss creates peat bogs used for fuel. The Sphagnum moss creates peat bogs used for fuel. Info about Sphagnum Info about Sphagnum Info about Sphagnum Info about Sphagnum

Vascular Plants Vascular Plants have true roots, stems and leaves Vascular Plants have true roots, stems and leaves Xylem: tissue that transports water and solutes Xylem: tissue that transports water and solutes Phloem: tissue that transports sugar made by photosynthesis Phloem: tissue that transports sugar made by photosynthesis Groups: Groups: Seedless (ferns) Seedless (ferns) Seed plants: seeds are multicellular structures that contain an embryo Seed plants: seeds are multicellular structures that contain an embryo

Seedless Plants (ferns) Rhizomes: underground stems that produce roots. Rhizomes: underground stems that produce roots. Fiddleheads: coiled immature leaves that arise from ferns Fiddleheads: coiled immature leaves that arise from ferns Fronds: mature leaves of ferns Fronds: mature leaves of ferns Sori: clusters of sporangia where spores are formed on the underside of fronds Sori: clusters of sporangia where spores are formed on the underside of fronds Info: Info: Info:

Seed Plants: Gymnosperms “naked seed” “naked seed” Divisions: Divisions: Cycadophyta and Gingkophyta Cycadophyta and GingkophytaGingkophyta Coniferophyta Coniferophyta Coniferophyta Pines, cedars, junipers, redwoods, firs, spruces, yews, Pines, cedars, junipers, redwoods, firs, spruces, yews, Woody plants with needles and cones Woody plants with needles and cones Contain both male and female cones on the same tree Contain both male and female cones on the same tree

Seed Plants: Angiosperms Characteristics Dominate the plant world Dominate the plant world Herbaceous and woody species Herbaceous and woody species Seeds are enclosed in protective fruits Seeds are enclosed in protective fruits Many have coevolved with insects Many have coevolved with insects Many have highly advanced vascular systems Many have highly advanced vascular systems

Angiosperms: Classification Most plants are from this major division: Anthophyta Most plants are from this major division: Anthophyta Divided into 2 groups: Divided into 2 groups: Monocots Monocots Dicots Dicots

Monocots Have one cotyledon (seed leaf) in their embryo Have one cotyledon (seed leaf) in their embryo Parallel venation in the leaves Parallel venation in the leaves 3 part symmetry of the flower parts 3 part symmetry of the flower parts Examples: palm trees, lilies, onions, corn, grasses Examples: palm trees, lilies, onions, corn, grasses Pictures: Pictures: Pictures:

Dicots 2 cotyledons in embryo 2 cotyledons in embryo Net venation in the leaves Net venation in the leaves 4 or 5 part symmetry in the flower 4 or 5 part symmetry in the flower Examples: magnolias, maples, cacti, most flowering plants and forest trees Examples: magnolias, maples, cacti, most flowering plants and forest trees Pictures: Pictures: Pictures:

Plant Kingdom vascular plants non-vascular plants seed plants ferns angiosperms gymnosperms monocot dicots