1. Plants  plants dominate most of the land on Earth  plants and plant products are all around us, in the products we use and the foods we eat

2. Classification  evolved from charophytes, a group of green algae (belong to the kingdom Protista)

3. Classification Cont’d…  plants are classified into four major groups: (1) bryophytes, (2) pteridophystes, (3) gymnosperms & (4) angiosperms

4. Characteristics  (almost) all plants…  are multicellular eukaryotic organisms  photosynthesize  have cell walls made of cellulose  are sessile (don’t move from place to place)  yet plants are very diverse

5. Life Cycle  plants have an alternation of generations life cycle  a plant in the diploid stage is called a sporophyte  sporophyte’s diploid cells divide by meiosis to produce haploid cells which form asexual spores  the spores grow into gametophyte individuals  gametophytes mature and produce haploid sex cells (gametes)  gametes undergo fertilization to form diploid zygotes  zygotes grow into sporophyte individuals, and the cycle continues

6. Early Adaptations for Life on Land  most plant species living today live on the land but primitive ancestors of today’s plants, however, lived in the water  To adapt to land plants developed…  cuticles : waterproof, waxy coating made by the epidermis of plants to prevent water loss  stomata: small openings in the epidermis of a plant that can open and close to allow gas exchange

7. Bryophytes  bryophytes are the simplest of land plants and include the mosses, liverworts,and hornworts  have a protective cuticle and stomata but they do not have specialized vascular tissue or true leaves, roots, or seeds  only grow a few centimetres in height  depend on water (dew or rain)to carry sperm to ovum for reproduction and only the gametophyte is photosynthetic

8. Life Cycle of a Moss

9. Lycophytes and Pterophytes  the next major adaptation by land plants was the development of vascular tissue  vascular tissue consists of xylem and phloem which transports water and nutrients  plants with vascular tissue can grow to great heights and access more sunlight  lignin is a very strong component of vascular tissue that makes cell walls more rigid

10. Lycophytes and Pterophytes Cont’d…  lycophytes (club mosses) and pterophytes (ferns) are seedless vascular plants with large simple roots and stems  many have developed symbiotic mycorrhizal relationships that help them obtain water and other nutrients from the soil  similar to bryophytes, reproduce sexually using sperm and eggs but the sporophytes are photosynthetic and much larger than the gametophytes

11. Life Cycle of a Fern

12.  the entire male gametophyte is carried from one plant to another by the wind or by animals, instead of travelling through water  not restricted to reproduction over short distances in wet conditions  are the dominant land plants on Earth Gymnosperms and Angiosperms: The Seed Plants

13.  pollen grains are waterproof capsules that contain haploid male gametophytes  pollination occurs when the male gamete in a pollen grain penetrates an ovule containing a female gametophyte  male gamete fertilizes egg, producing a diploid zygote, or embryo, which becomes a seed Gymnosperms and Angiosperms: The Seed Plants Cont’d…

14.  the food supply in the seed gives the embryo nutrients to grow a small root, stem, and leaves before it can photosynthesize  food supply is a concentrated mix of starch, plant oils, and some protein  seeds are a VERY important food source for many animals

15. Gymnosperms: The Conifers  gymnosperms include the coniferous trees and other less well known groups of plants  cones are the reproductive structures of conifers  male cones produce and release pollen, and female cones produce eggs  when an egg is successfully pollinated and fertilized within a female cone, an embryo develops within a seed in the cone

16.  many of these are woody trees, and most have needle- or scale- like leaves  narrow leaves and thick cuticles are adaptations that help the trees reduce water loss Gymnosperms: The Conifers Cont’d…

17.  gymnosperms have large, shallow root systems that form a mycorrhizal relationship with symbiotic fungi

18. Angiosperms: The Flowering Plants  more than 90% of all modern plant species are angiosperms  angiosperms : flowering plants

19. Angiosperms: The Flowering Plants  flowers: reproductive structures that produce both pollen and eggs  in female flower parts, the eggs are protected in an enclosed ovary

20. Angiosperms: The Flowering Plants  after fertilization, seeds form within the ovary and the outer tissues of the ovary become a fruit  main function of the fruit is to disperse the seeds  gizmo

21. Angiosperms: The Flowering Plants  the development of flowers and fruits is key to the success of the angiosperms  flowers are specialized for the way the plant is pollinated (ex. flowering plants that depend on animals for pollination are colorful, fragrant and have nectar)

22. Angiosperms: The Flowering Plants  each fruit is adapted to protect and disperse the seeds within it using wind, water, and other organisms (ex. burdock fruit has needles that stick to animals)

23. Homework  answer 3.2 questions # 2-7