Presentation on theme: "Plant Diversity Chapter 22 Miller & Levine Text Biology 112."— Presentation transcript:
Plant Diversity Chapter 22 Miller & Levine Text Biology 112
Introduction to Plants 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??
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
What do Plants Need? 1. Sunlight 2. Water & Minerals 3. Gas Exchange 4. Movement of Water and Nutrients
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”
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.
Overview of the Plant Kingdom Botanists divide the plant kingdom into 4 groups based on three important features: 1.Water-conducting tissues 2.Seeds 3. Flowers
Types of Plants 235,000 Flowering Plants (Angiosperms) Mosses & Relatives 15,600 species Cone-bearing plants 760 species (gymnosperms) Ferns & Relatives 11,000 species
Bryophytes (Non-Vascular) 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 No Xylem or Phloem
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
Seedless Vascular Plants (Ferns & Relatives) Dominant land plant 300 million years ago Most are now extinct
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
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
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
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
The veins of monocot leaves are parallel to each other The leaves of dicots usually have netlike veins **See other characteristics on page 570
Monocot Examples Tulips, daffodils, irises, lilies, palm trees
Dicot Examples Buttercups, peas, roses, sunflowers, maple trees, and dandelions
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!
Roots, Stems & Leaves “Principal organs of seed plants”
Roots – Try This: 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
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
#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.
Fibrous Roots - A cabbage seedling with white, fibrous roots snaking through the soil
STEMS Stems have 3 important functions: 1.Produce leaves, branches, flowers 2.Hold leaves up to sunlight 3.Transport substances between roots and leaves
Leaves – (focus for Friday’s Lab) The structure of a leaf is optimized for absorbing light and carrying out photosynthesis.
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
Vascular tissue= veins for the plant Phloem- transports food (sugar- 2ways) Xylem- transports water (1 way) 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. No vascular tissue No true roots, stems or leaves Example: Moss 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