Why plants are important - explorers.com/wildflowers/importance_of_plants _and_plant_c.htmhttp:// explorers.com/wildflowers/importance_of_plants _and_plant_c.htm Cool plant Facts:

Pretest The World of Plants (15 minutes)

Plant Diversity Chapter 22 Miller & Levine Text Biology 112

Introduction to Plants (Chapter 22) Plants… Provide the base for food chain 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?? Botany

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 haploid (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

Water-Conducting Tissues Evolved as an adaptation to land Absence – no xylem or phloem Presence of tissue: –Xylem Carries water and nutrients that enter the plant in the roots up through the stem and out to all parts of the leaves –Phloem Parallel to the xylem Carries sugar (energy) produced in leaves (site of photosynthesis) to all parts of the plant

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 –Do not flower so no seeds –They produce spores Commonly found in wetlands, rain forests, and roadside ditches Generally less than 20cm tall 3 classes: mosses, liverworts, and hornworts No Xylem or Phloem

Liverwort Mosses Hornwort

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 osmosis / 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 (Vascular) Divided into two groups –Gymnosperms (naked seed) –Angiosperms (covered seed) What makes them different? –Seed type is the main criterion for distinguishing the two major seed-bearing groups; gymnosperms and angiosperms –Greek: sperma “seed”, gymnos “naked”, and angeion “vessel ” Why are they successful? –Reproductive Adaptations and an improved vascular system largely account for the success of seed plants –The most widely distributed and complex group of plants on Earth – known seed plants –Have separate male and female gametophytes, as well as roots, stems and leaves.

Seed Plants - Gymnosperms The most ancient surviving seed plants are the gymnosperms Seeds are often found in a cone Represent all seed plants that DO NOT form flowers (therefore do not have seeds enclosed within a fruit) The most numerous and widespread are the conifers

Gymnosperms: 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 Plants – Angiosperms (Flowering Plants) There are thousands of different kinds of flowering plants They range from tiny pond-surface plants, which are less than 1 mm long to trees 100 m tall. Angiosperms ALL produce seeds in reproductive structures called flowers. Then, as the seeds mature, the flower changes into a fruit. Angiosperms produce seeds that are enclosed and protected inside the fruit, which is formed by the flower. Mature seeds are scattered, or dispersed, along with the fruit