- An Overview of Plants

2. - An Overview of Plants • Characteristics: • Range in size • Microscopic water ferns to giant sequoia trees • Have roots • Have cell walls • All plants need water • Some plants cannot live unless they are submerged in freshwater or saltwater. • Not all plants live only on land • All plants are many-celled, and most contain green pigment called chlorophyll.

3. You notice green scum floating on the surface of a pond. How can you tell whether these organisms are plants? • Answer? • Examine them under the microscope. If they are many-celled and have chloroplasts, cell walls, and nuclei, they are plants!

4. Scientists think that plants evolved directly from green algae. • 1st plants on land could only survive in damp areas. • Oldest fossil plants are about 420 million yrs old. • Pine trees existed 350 million yrs ago • Flowering plants did not exist until 120 million yrs ago. • Their exact origin is unknown

5. Adaptations to Land • Plants that live on land need adaptations to help them conserve water. • Cuticle- waxy, protective layer on leaves of plants • Slows the loss of water • Cellulose- an organic compound found in plant cell walls • Found in cell walls to provide structure and support • Chemical compound that forms tangled fibers in the cell walls of plants.

6. Classification of Plants • Vascular or Nonvascular?? • Vascular Plants • Plants that have tube-like structures for transporting substances. • Have vessels to transport water and nutrients • Why would vascular tissue be an advantage to plants adapting to life on land? • Answer: • Vascular tissue carries water, minerals, and nutrients throughout the plant so it can exist away from water • Nonvascular Plants • Do not have these tube-like structures and use other ways to move water and substances. Contain spores, rhizoids, and cell walls.

7. Examples of Vascular Plants • Fern • Horsetail • Pine Tree • Examples of Nonvascular Plants • Mosses • Liverworts • Hornworts • Algae How do the cells of nonvascular plants get water and nutrients if they do not have vessels? Answer: Each cell absorbs water and nutrients on its own.

8. Seedless Nonvascular Plants • Mosses- a seedless, rootless plant with leaf-like growths. • Grow on tree trunks and rocks or the ground • Found in damp areas, some live in deserts • Liverworts- means “herb for liver” • 9th century thought to be useful in treating liver diseases. • Rootless with flattened bodies • Hornworts- flattened body Spore-producing structure looks like horns of cattle

9. Nonvascular Plants + Environment • Mosses and liverworts can grow in soils where other plants can not grow. • Spores of mosses and liverworts are carried by the wind. • Pioneer species • The first to grow in a new or disturbed areas. • Mosses and liverworts that are among the first plants to inhabit a new environment are called pioneer species. • Liverworts and mosses are the first plants to grow in new environments.

10. Seedless Vascular Plants • Ferns, ground pines, spike mosses, and horsetails. • Ferns are the most abundant of the seedless vascular plants. • Have vascular tissue • Have stems, leaves, and roots • Produce spores • Club Mosses • Needle-like leaves • Horsetails • Stem is jointed and has a hollow center surrounded by a ring of vascular tissue

11. Importance of Seedless Plants • As plant materials die and build up they are compacted and compressed and eventually turn into coal. • Ancient seedless plants compacted and eventually turned into the coal we use today. • Similar process today, takes place in bogs • Bogs- poorly drained areas with spongy, wet ground that is comprised mainly of dead and decaying plants • Peat- remains of sphagnum moss • Peat is actually the earliest stage of coal.

12. Seed Plants • Have leaves, stems, roots and vascular tissue • 2 major classifications of seed plants • Gymnosperms and angiosperms • Leaves • Upper and lower surface is epidermis • Organs of the plant where the food-making process occurs (photosynthesis) • Major function- make food • Stomata- small pores on leaf surface allowing carbon dioxide in • Each stoma is surrounded by two guard cells that open and close it

13. Palisade layer • Just below the upper epidermis • Closely packed cells under the epidermis of leaves contains chloroplasts. • Spongy layer- loosely arranged cell layer in the leaf • Stems • Moving materials between leaves and roots • Stores food and water • Supporting the plant • Roots • Anchor the plant • Absorb water • Store food

14. Vascular tissue • Xylem- vessels that transport substances from the roots to other parts of the plant • Phloem- vessels that move food from leaves to other plant parts • Cambium- tissue that produces new xylem and phloem cells

15. Gymnosperms • Vascular plants that produce seeds that are not protected by fruit • “naked seed” • DO NOT have flowers • Ex. Ginkgoes, conifers, cycads • All conifers produce male and female cones • Reproductive structure • The oldest trees alive are gymnosperms

16. Angiosperm • Vascular plant that flowers and produces fruits with one or more seeds. • Have a wide variety of flowers and fruits • The most common type of plants on Earth

17. Monocots • “mono” – “one” • Have one cotyledon inside their seeds • Ex. Corn, rice, wheat, and barley • Have flower parts in multiples of three • Leaves more narrow than long • Vascular bundles are parallel veins in leaves

18. Dicots • Di means “two” • Has two cotyledons inside their seeds • Flower parts in multiples of four or five • Ex. Peanuts, green beans, apples, and oranges. • Vascular bundles are the network of veins in leaves http://glencoe.mcgraw-hill.com/sites/dl/free/0078617022/164213/00044690.html

19. Quiz • Label the following plants as dicot or monocot 3. 1. 4. 2.

20. Quiz • Label each plant as vascular or nonvascular. 1. 3. 2. 4.