Chapter 22Chapter 22

Plant Evolution and ClassificationPlant Evolution and Classification

EvolutionEvolution

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 Many plants that grew during the carboniferous

period (280 mya) provide us with our fossil fuels.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 SurvivalAdaptations for Land Survival

Cuticle: waxy protective coveringCuticle: waxy protective covering Multicellular gametangia: structures that protect Multicellular gametangia: structures that protect

gametes during developmentgametes during development Vascular Tissue: complex tissues that transport water Vascular Tissue: complex tissues that transport water

and food and help support the weight of the plant and food and help support the weight of the plant (roots, stems, leaves)(roots, stems, leaves)

Spores: resistant reproductive cells (ferns)Spores: resistant reproductive cells (ferns) Seeds: protect and nourish embryo (gymno- and Seeds: protect and nourish embryo (gymno- and

angiosperms)angiosperms)

ReproductionReproduction

Alternation of GenerationsAlternation of Generations Plants and Algae undergo this life cycle.Plants and Algae undergo this life cycle.

Gametophyte: haploid multicellular structure that Gametophyte: haploid multicellular structure that produces gametes.produces gametes.

Sporophyte: developed from the zygote; produces Sporophyte: developed from the zygote; produces sporangia which in turn form the gametophyte sporangia which in turn form the gametophyte structure. structure.

Nonvascular PlantsNonvascular Plants

Nonvascular PlantsNonvascular Plants Have no true roots, stems or leavesHave no true roots, stems or leaves Examples are mosses, liverworts Examples are mosses, liverworts and hornworts (Division Bryophyta)and hornworts (Division Bryophyta) DescriptionDescription

Lie close to the ground to absorb waterLie close to the ground to absorb water Gametophyte is the obvious carpet-like structureGametophyte is the obvious carpet-like structure Rhizoids are root-like structures that act as anchorsRhizoids are root-like structures that act as anchors Sporophyte is the stalk-like structure that produces Sporophyte is the stalk-like structure that produces

sporesspores

Ecology of MossesEcology of Mosses

Rhizoids help prevent erosion.Rhizoids help prevent erosion. Mosses are often pioneer species in the Mosses are often pioneer species in the

development of new biological communities.development of new biological communities. The The SphagnumSphagnum moss creates peat bogs used moss creates peat bogs used

for fuel.for fuel. Info about Sphagnum

Vascular PlantsVascular Plants

Vascular Plants have true roots, stems and leavesVascular Plants have true roots, stems and leaves Xylem: tissue that transports water and solutesXylem: tissue that transports water and solutes Phloem: tissue that transports sugar made by Phloem: tissue that transports sugar made by

photosynthesisphotosynthesis Groups:Groups:

Seedless (ferns)Seedless (ferns) Seed plants: seeds are multicellular structures that Seed plants: seeds are multicellular structures that

contain an embryocontain an embryo

Seedless Plants (ferns)Seedless Plants (ferns)

Rhizomes: underground stems that produce roots.Rhizomes: underground stems that produce roots. Fiddleheads: coiled immature leaves that arise from Fiddleheads: coiled immature leaves that arise from

fernsferns Fronds: mature leaves of fernsFronds: mature leaves of ferns Sori: clusters of sporangia where spores are formed Sori: clusters of sporangia where spores are formed

on the underside of frondson the underside of fronds Info:

Seed Plants: GymnospermsSeed Plants: Gymnosperms ““naked seed”naked seed” Divisions: Divisions:

Cycadophyta and Cycadophyta and Gingkophyta ConiferophytaConiferophyta

Pines, cedars, junipers, redwoods, firs, spruces, yews, Pines, cedars, junipers, redwoods, firs, spruces, yews, Woody plants with needles and conesWoody plants with needles and cones Contain both male and female cones on the same treeContain both male and female cones on the same tree

Seed Plants: AngiospermsSeed Plants: AngiospermsCharacteristicsCharacteristics

Dominate the plant worldDominate the plant world Herbaceous and woody speciesHerbaceous and woody species Seeds are enclosed in protective fruitsSeeds are enclosed in protective fruits Many have coevolved with insectsMany have coevolved with insects Many have highly advanced vascular systemsMany have highly advanced vascular systems

Angiosperms:Angiosperms:ClassificationClassification

Most plants are from this major division: Most plants are from this major division: AnthophytaAnthophyta

Divided into 2 groups:Divided into 2 groups: MonocotsMonocots DicotsDicots

MonocotsMonocots

Have one cotyledon (seed leaf) in their embryoHave one cotyledon (seed leaf) in their embryo Parallel venation in the leavesParallel venation in the leaves 3 part symmetry of the flower parts3 part symmetry of the flower parts Examples: palm trees, lilies, onions, corn, Examples: palm trees, lilies, onions, corn,

grassesgrasses Pictures:Pictures:

DicotsDicots

2 cotyledons in embryo2 cotyledons in embryo Net venation in the leavesNet venation in the leaves 4 or 5 part symmetry in the flower4 or 5 part symmetry in the flower Examples: magnolias, maples, cacti, most Examples: magnolias, maples, cacti, most

flowering plants and forest treesflowering plants and forest trees Pictures:Pictures:

Plant Kingdom

vascular plants

non-vascular plants

seed plantsferns

angiosperms

gymnosperms

monocot

dicots