1. Botany Unit Notes Part I

2. What is a Plant? When you are asked, “what color is life?”, the color that comes to mind is usually green! It is no wonder that all of Earth’s living systems ultimately depend upon plants

3. What is a Plant? Plants are multicellular eukaryotes that have cell walls made of cellulose Many plants undergo photosynthesis Plants include: trees, shrubs, and grasses Also ferns and mosses Most are autotrophs except for a few parasitic plants and saprobes Saprobes feed on decaying organic material

4. What Plants Need to Survive Sunlight ~ plants use the energy from the sun to carry out photosynthesis Water and Minerals ~ all cells require water and it is used during photosynthesis plants absorb minerals from the soil needed for plant growth

5. What Plants Need to Survive Gas Exchange ~ plants need Carbon Dioxide and even Oxygen to carry out photosynthesis Movement of Water and Nutrients: The water and minerals taken up by the roots of plants needs to be transported to the structures that carry out photosynthesis These are hundreds of feet in the air sometimes!

6. The Origin of Plants It all started in the water Some scientists believe that the first plants came from ancient, photosynthetic prokaryotes The oldest known fossils of plants show them to be around 500 Million years old Green Algae

7. The Origin of Plants

8. Overview of the Plant Kingdom Botanists divide the Plant Kingdom into 4 groups based upon three features: Water-conducting tissues Seeds Flowers The Four Groups Cone bearing ~ 760 species Ferns & their relatives ~ 11,000 species Mosses & their relatives ~ 15,600 species Flowering plants ~ 235,000 species The most abundant plants of today are the flowering plants making up 90% of all plants on Earth

9. Overview of the Plant Kingdom

10. Evolution of Land Plants As plants evolved they obtained important traits: Non-vascular tissues (primitive) Early plants that needed to be near water to diffuse it into their cells (bryophytes: mosses, liverworts, hornworts) Vascular plants (seedless came first) Plants that have specialized tissues capable of drawing water up from the soil through roots (Ferns & horsetails) Seed producing plants Plants able to protect their young in a durable seed (Gymnosperms: Cycads, Gnetophytes, Conifers, etc) Seeds enclosed in fruits (advanced) Plants that adapted an attractive fruit to have animals disperse their young (Angiosperms: Grasses, fruit trees, shrubs, etc)

11. Seedless Vascular Plants The first seedless vascular plants arrived on land around 420 million years ago The new adaptation of transporting water and nutrients through the plant using vascular tissue allowed them to grow much taller than the mosses and other bryophytes

12. Vascular Tissues Vascular tissues allowed plants to grow taller & transport water and nutrients Xylem moves water up the plant from the roots Phloem transports sugars and nutrients of photosynthesis down through the plant

13. Seedless Vascular Plants This group contains the club mosses, horsetails, and ferns What makes them different from the earlier plants is that they have true roots, stems, and leaves Club Mosses – Phylum Lycophyta, millions of years ago they existed as tall plants towering over 100 ft! Today they are small plants living in moist woodlands

14. Seedless Vascular Plants Horsetail – Phylum Arthrophyta The only living species left of this phylum All plants in this Phylum belong to the Genus Equisetum and has true roots, leaves, and stems They reproduce by way of spores released from specialized structures They look like tall grasses and are found near water most often They are popular pond plants and used for decoration in Asian gardens

15. Seedless Vascular Plants Ferns are members of the Phylum Pterophyta Thought to have begun around 350 mya Survivors of millions of years and having 11,000 different species existing today True vascular tissues, strong roots, and underground stems called rhizomes

16. Life Cycle of Ferns Ferns and relatives are actually the final stage of their lifecycle Called a Diploid Sporophyte Spores are haploid forming young gametophytes The gametophytes produce sperm and egg and then fertilize the egg After fertilization, a mature sporophyte grows from the gametophyte