2 Plant EvolutionPlant: multicellular, photosynthetic eukaryotic organism that contains tissues and organs with specialized structures and functionsPlants share a common ancestor with green algae.Plants developed derived traits (adaptations) to be able to live on land.CuticleStomataVascular tissueReproductive strategiesSeeds
3 PLANTLEAF performs photosynthesisNot picturedVascular tissues: specialized transport tissues that move water and nutrients from the roots to the rest of the plant; provides supportReproductive strategies: adaptations of gametes and mutually beneficial relationships with other living thingsSeeds: Seed coats protect embryo of new plants as they scatter on landCUTICLE reduces water loss; STOMATA allow gas exchange (photosynthesisand cellular respiration)STEM supports plant (and may perform photosynthesis)ALGAESurrounding water supports the algaeWHOLE ALGAE performs photosynthesis; absorbs water, CO2, and minerals from the waterROOTS anchor plant; absorb water and minerals from the soil (aided by mycorrhizal fungi)HOLDFAST anchors the algae
4 Plant Classification Two main categories: Nonvascular Plants (earliest to diverge)Called BryophytesCommon examples: mosses, hornworts, and liverwortsSmall plantsLack true leaves; use root-like rhizoids to anchor them into to a surfaceLive in damp, shady areas to assist in providing water to tissuesVascular Plants (evolved later)Seedless Plants (ferns) and Seed PlantsContain a xylem and phloemHave well-developed root systemRigid stem
5 Vascular Seedless Plants - Ferns Tend to live in damp, shady areasWater is need for flagellated sperm to reach the egg to reproduce new generations of the plants.
6 Vascular Seed PlantsThe appearance of seeds is a major evolutionary step.Pollen grains transport sperm rather than water.Seed Structure – protects embryo:Seed coat: protective coatingEmbryo: growing, developing new plantCotyledons: store food or help absorb food for the growing embryoMonocotyledons – have one cotyledonDicotyledons – have two cotyledonsLocation of SeedsAngiosperms – seeds are found in a fruitGymnosperms – seeds are NOT part of a fruit; naked seeds
7 Gymnosperms – Naked Seed Plants Gymnosperms diverged before angiosperms. Fruits are a more recent adaptation.Division Coniferophyta:Male cones produce pollen, which carries sperm.Female cones are larger and more open to allow the sperm to collect.Female cones remain on the plant until seeds are mature.When the cone drops from the tree, seeds are spread.
8 Angiosperms – Fruit-bearing, Flowering Plants Flowers are reproductive structures in plants.Sepal: protects flower budsPetal: attracts pollinators and provides landing padStamen – MALE reproductive organ; filament supports the anther; anther produces pollen (sperm)Pistil or Carpel – FEMALE reproductive organ; pollination occurs at stigma; embryo (SEEDS) develop in the ovary; fruits form from the ovary
9 Fruits – Seed Dispersal Fruits are seed dispersal adaptations.
12 Categories of Angiosperms Monocot is on the leftOat plantDicot is on the rightBean plantNotice the differences in the two plants.
13 Categories of Angiosperms In monocots, the vascular bundles in the stem cross section are usually scattered or more complex of an arrangement as compared to dicots.The vascular bundles in the stem cross section of dicots are arranged in a circle, or ring.