Domain Eukarya: Kingdom Plantae non-vascular plants
Land plants descended from a green algae ancestor Some key characteristics of land plants are shared with green algae, like Multicellular, eukaryotic, autotrophs Their cell walls have cellulose and have the same photosynthetic pigments chlorophyll a and b and carotenoids Among the green algae plants are closest Related to charophytes There are some key traits, that land plants share only with Charophytes
Charophytes: a group of multicellular green algae that inhabit shallow waters on ponds and lakes. Land Plants are different because about 500 million years ago they moved on to land What benefits were there for photosynthetic organisms to move on to land? air filters less sunlight than water. There's more light for photosynthesis. air has more CO2 than water. There's more fuel for photosynthesis. early terrestrial habitats lacked competitors, pathogens or predators/herbivores. But moving on to land has its own set of problems: Drying out, no support, resources are in separate areas, reproduction
Reproductive life cycle that consists of a haploid multicellular stage and a multicellular diploid stage Alternation of Generations Zygote Embryo Sporophyte embryo zygote Sporangium Meiosis Spores (not flagellated) Gametophyte Gametangia (Antheridium and Archegonium) Gametes (sperm and egg) fertilization
Think pair and share Identify each structure as either haploid or diploid: A. Sporphyte B. Spore C. Gametophyte D. Zygote E. Sperm F. Egg Identify the type of cell division that gives rise to each of the following: A. Gametes B. Spores C. Zygote sporophyte D. Spore gametophyte
What traits appeared in The evolution of plants? How did these traits Help plants be better adapted To life on land? Groups of plants: -Bryophytes (nonvascular plants) -Seedless vascular plants - Seed plants: Gymnosperms Angiosperms
Early adaptations of land plants Prevent water loss Cuticle Regulation of water loss and Gas exchange: stomata Reproduction without water: spores housed in sporangia gametes housed in gametangia internal fertilization embryo attached
Reproduction adaptations - spores housed in sporangia - gametes housed in gametangia - internal fertilization - embryo develops protected by archegonia tissue
Bryophytes: Non vascular plants lack vascular tissue (hence, lack true organs, leaves, stems and roots) The relatively undifferentiated body of such plants is known as the thallus root like structures are called rhizoids (formed of single cells not tissues like roots) have a very thin waxy cuticle release flagellated sperm directly into the environment (and so need water--at least a thin film--for reproduction) have a dominant gametophyte generation, and a short-lived sporophyte
Phylum Hepatophyta (liverworts) From the Latin hepaticus, meaning liver", describing the liver shaped gametophytes of Marchanita Gametophyte body is the thallus Gametophyte has Umbrella shaped gametophores Gametophores have Antheridia or archegonia Fertilization in archegonia Sporophyte is very small Develops inside archegonia
Phylum Anthocerophyta (hornworts) From the Greek Kera, meaning horn", describing the horn shaped sporophytes Sporophyte continues to grow and eventually Ruptures and releases spores Gametophyte body grows horizontally
Phylum Bryophyta (mosses) Mosses gametophytes grow more vertically. Have vascular cells the male and female gametophyte are not as obviously morphologically distinct.
Sphagnum is an ecological and economic important moss About 1% of the earth's surface (about half the area of the U.S.) is occupied by peat bogs. Peat bogs are made up of dead Sphagnum plus all the grasses and other plants that grow with the moss Sphagnum one of the most abundant plants on earth. These bogs are highly acidic, they are not hospitable to bacteria, and decomposition of the moss occurs extremely slowly, This can be seen clearly in the preservation of the Bog People of Denmark. The peat bogs store huge amounts of carbon (400 billion metric tons)
Sphagnum is an ecological and economic important moss Dried peat is an important fuel for domestic and industrial use in Ireland and Canada. So much for the stored carbon!
Comparing liverworts, hornworts and mosses Which generation is the dominant one? Which generation is dependent on the other one? How does the individual bryophyte disperse? Why are these plants not totally adapted to terrestrial environments?