Plants (Kingdom Plantae) Multicellular eukaryotes Photoautotrophs Terrestrial? –Not all plants are terrestrial Return to water from land Move to land was a major step

Move to Land Required Significant Adaptations Water uptake and loss Gas exchange Reproduction Support

Move to Land Plants probably evolved from a group of green algae called the charophytes Are a fringe species exhibiting multicellular traits Why a fringe species?

Features Common to Green Algae and Plants Chlorophyll a and other accessory pigments (Chl b,  -carotene) thylakoid membranes stacked into grana

Features Common to Green Algae and Plants Chlorophyll a and other accessory pigments (Chl b,  -carotene) similar photosynthesizing organelles cell walls of cellulose store carbohydrates as starch alternation of generation

Highlights of Plant Evolution Four major periods Move onto land (~ mya) –prevent desiccation of whole plant –protect reproductive structures –Features seen in mosses (bryophytes)

Highlights of Plant Evolution Evolution of vascular tissue and diversification (~400 mya) –simple diffusion not an option –Mosses - water-conducting tubes –transport and support –larger body size These are features first seen in ferns, horsetail, whisk ferns ****Similar protection of gametes

Horsetail Whisk Fern

Highlights of Plant Evolution Evolution of seed (~360 mya) –additional protection from desiccation and predation –dispersal

Highlights of Plant Evolution Emergence of flowering plants (~130 mya) –Seeds in protective ovary –Expanded potential for diversity –Complex structure with great potential for adaptation –Greater sexual reproductive success –Coevolution between insects and angiosperms

Nontracheophytes Mosses, liverworts and hornworts Probably closest to ancestral form protected gametangia lack vascular tissue Encrusting Water needed for fertilization

Gametophyte Sporophyte Sporophyte relies on gametophyte for nutrients

Nonseed Tracheophytes Plants Ferns, horsetail, club mosses Retain some traits of mosses Evolved some traits also seen in seed- producing vascular plants

Traits Shared with Nontracheophytes Antheridia and archegonia retain similar structure Require water/moisture for sexual reproduction Production of spores

Traits Shared with Seed-Producing Plants Vascular tissue - greater body size Sporophyte is dominant stage of life cycle

Gametophyte Sporophyte

Seedless tracheophytes were the dominant vascular plants for ~ 50 million years Continents in tropical/subtropical zone As continents drifted away from equator, conditions changed Seed-producing plants were present during height of seedless vascular plant success

Rise of Seed-Producing Tracheophytes Well suited for environmental changes Gametophyte smaller and retained in moist tissues of sporophyte Pollination rather than swimming sperm Evolution of seed gymnosperms and angiosperms

Gymnosperm “naked seed” still have a seed coat four divisions Coniferophyta best known evergreens needle-shaped leaves, thick cuticle

Gametophyte Sporophyte Gametophyte passes within sporophyte

“protected seed” most diverse group –235,000 known species vs. 721 species of gymnosperms One division - Anthophyta Two classes –Monocotyledones –Dicotyledones Angiosperms

successful and effective design different themes of the same design

Gametophyte Sporophyte Gametophyte passes within sporophyte

Develops into fruit Develop into seeds