1. Chapter 22 Miller & Levine Text Biology 112
Plant Diversity
Chapter 22
Miller & Levine Text
Biology 112

2. Introduction to Plants
Provide the base for food chains on land
Provide shade, shelter and oxygen for all animals
Oldest fossil evidence of plants dates from about 470 million years ago!
What is the name of the science of studying plants??

3. Kingdom Plantae Multicellular Eukaryotic
Carry out photosynthesis using green pigments called chlorophyll
Include trees, shrubs, grasses, mosses and ferns
Most are autotrophs
Cell Walls made of cellulose

4. What do Plants Need? 1. Sunlight 2. Water & Minerals 3. Gas Exchange
4. Movement of Water and Nutrients

5. Plant Life Cycle
Two alternating phases, a diploid (2N) phase called the sporophyte generation and a hapoid (N) known as gametophyte generation
These alternating phases are known as “alternation of generations”

6. Early Plants
For most of Earth’s history plants did not exist. Life was concentrated in oceans, lakes and streams…Oxygen came from algae and cyanobacteria
The first plants evolved from an organism much like the multicellular green algae living today.

7. Overview of the Plant Kingdom
Botanists divide the plant kingdom into 4 groups based on three important features:
Water-conducting tissues
Seeds
3. Flowers

9. Types of Plants 235,000 Flowering Plants (Angiosperms)
Cone-bearing plants 760 species (gymnosperms)
Ferns & Relatives 11,000 species
Mosses & Relatives
15,600 species

10. Bryophytes (Non-Vascular)
No Xylem or Phloem
Confined to moist habitats b/c they need water for sexual reproduction
Commonly found in wetlands, rain forests, and roadside ditches
Generally less than 20cm tall
3 classes: mosses, liverworts, and hornworts

11. Liverwort

12. Hornwort

13. Bryophytes Have leaflike, stemlike and rootlike organs
Have rhizoids (fine-like roots) that anchor the plant
Water and nutrients move from cell to cell by diffusion
Mosses are the most common and they hold a lot of water – this sponge like feature makes them useful in oil spills, and potting soils

14. Moss

15. Seedless Vascular Plants (Ferns & Relatives)
Dominant land plant 300 million years ago
Most are now extinct

16. Seed Plants - Gymnosperm
Divided into 2 groups: Gymnosperms & Angiosperms
GYMNOSPERMS:
The most ancient surviving seed plants are the gymnosperms (naked seeds)
Seeds often found in a cone

17. Gymnosperms: The Conifers
Cone bearing woody trees and shrubs
Leaves are usually needlelike
Most are evergreen (don’t drop their leaves in the Autumn)
Conifers DO shed their needles, just not all at once – usually 2 to 4 years
Grow in many different environments
600 species (pine, fir, spruce, cedar, hemlock, sequoias
Produce useful products, ie. lumber/paper

18. Seed Plant – Angiosperms: Flowering Plants
There are thousands of different kinds of flowering plants
Angiosperms ALL produce seeds in reproductive structures called flowers.
Flowers contain ovaries, which surround and protect the seed. Then, as the seeds mature, the flower changes into a fruit.
The name angiosperm means “covered seed”
Mature seeds are scattered, or dispersed, along with the fruit

19. Monocots & Dicots
Botanists are able to divide the 235,000 species of angiosperms into two large groups based on the structure of their seeds
Inside the seeds of angiosperms are tiny embryonic leaves called cotyledons. The seeds of one group of angiosperms have one cotyledon, called monocotyledons or monocots.
Other angiosperms have two cotyledons. These are called dicotyledons or dicots

20. The veins of monocot leaves are parallel to each other
The leaves of dicots usually have netlike veins
**See other characteristics on page 570

21. Monocot Examples
Tulips, daffodils, irises, lilies, palm trees

22. Dicot Examples
Buttercups, peas, roses, sunflowers, maple trees, and dandelions

23. Grass?
The leaf blade of grasses indicates whether they are monocots or dicots based on leaf veins.
To which group to grasses belong?
You are right if you said monocots!

24. Roots, Stems & Leaves “Principal organs of seed plants”

25. Roots – Try This: http://www.virted.org/Plants/RootsQuiz.html
Absorbs water and dissolved nutrients
Anchors plants to ground
Prevents erosion
Protection from soil bacteria and fungus
Transports water & nutrients
Holds plants upright against forces such as wind and rain

26. Roots – Two main types: Plants have taproots, fibrous roots or both
#1 Taproots - Characterized by having one main root (the taproot) from which smaller branch roots emerge. 
Make a plant hard to pull from the ground
Go far underground to reach water
Ex: dandelions, carrots, beets, radish 

27. Taproot

28. #2. Fibrous Roots –
Characterized by having a mass of similarly sized roots. 
Most monocots have fibrous root systems. 
Ex: grasses
Plants with fibrous roots systems are excellent for erosion control, because the mass of roots cling to soil particles.

29. Fibrous Roots - A cabbage seedling with white, fibrous roots snaking through the soil

30. Root Overview

31. STEMS Stems have 3 important functions:
Produce leaves, branches, flowers
Hold leaves up to sunlight
Transport substances between roots and leaves

33. Leaves – (focus for Friday’s Lab)
The structure of a leaf is optimized for absorbing light and carrying out photosynthesis.

34. Leaves
Photosynthetic organ of the plant, used to convert sunlight into food
Photosynthesis Equation:
Stomata: pores within the leaf that open to let CO2 in and O2 out. Guard cells open and close.
Cuticle: waxy covering on leaf that prevents water loss

35. Vascular tissue= veins for the plant
Phloem- transports food (sugar- 2ways)
Xylem- transports water (1 way)
No vascular tissue
No true roots, stems or leaves
Example: Moss
Seeds = embryo surrounded by endosperm (food for the baby plant)
Flowering plants
Non-flowering plants
Make cones, but no fruit or flowers
Example: conifers, fir trees, pine trees, etc.
Flower parts in 3 or multiples of 3
Parallel veins in leaf
Scattered vascular bundles in stem cross section
1 cotyledon (seed leaf
Ex. Tulip
Flower parts in 4/5 or multiples of 4/5
Netted veins in leaf
Ring of vascular bundles in stem cross section
2 cotyledon (seed leaf
Ex. Sunflower