The What & Why of Botany Introduction: Chapters 18 & 22.1
What is Botany? • Botany: plant biology, the study of plants. • What is considered a “plant”? • How did plants evolve? • What is a plant’s structure? • How do plants grow and develop? • How do plants interact with their environment?
What is a “Plant”? • Biologists like to put things into categories. • To answer the question, “What is a plant?”, we need to look at the major groups of living organisms. • The major groups of living organisms are called Kingdoms. • The 6 Kingdoms: Plantae, Animalia, Protista, Fungi, Archaebacteria, and Eubacteria. • The criteria used to place organisms into one of these 6 kingdoms is based on cell structure, modes of nutrition, and the level of complexity of each organism.
What is a “Plant”? • So, what exactly is a “plant”? • Plants: • Multicellular • Eukaryotic • Cell walls made of cellulose • Autotrophs • Carry out photosynthesis • Includes: • Trees, Shrubs, Grasses, Mosses, Ferns Level of Complexity Cell Structure Nutrition
What do Plants Need to Survive? • List 4 things plants need to survive. • 1) Sunlight – required for photosynthesis • 2) Water & Minerals – required for growth and photosynthesis • 3) Gas Exchange – require oxygen for respiration and carbon dioxide for photosynthesis • 4) Movement of Water and Nutrients – use roots, stems, and leaves
Where Did Plants Come From? • There are approximately 260,000 species of plants in the world today. • Plants are thought to have evolved from green algae and have been around for about 500 million years. • The oldest plant fossil dates back to about 450 million years ago. • About 350 million years ago, most of the Earth was covered by forests of primitive plants. • Flowering plants did not develop until about 65 million years ago, about the time when dinosaurs became extinct.
How Do We Classify Plants? • Based on reproductive strategy: • Spore – simple reproductive cell with hard, outer wall. • Seed – embryo, food supply, and protective coat. • Also, on how they obtain water: • Vascular – tube like structures to transport water from roots to leaves. • Nonvascular – only absorb water through roots.
Cone-bearing plants760 species Floweringplants235,000 species Ferns andtheir relatives11,000 species Mosses andtheir relatives15,600 species
Plant Classification Moss • Seedless, Nonvascular Plants (Bryophytes) • Mosses and Liverworts • Seedless, Vascular Plants (Pteridophytes) • Ferns and Horsetails • Seeded, Vascular Plants • Gymnosperms (Cone-bearing) • Angiosperms (Flower-bearing) • Monocot • Dicot Fern Gymnosperm Angiosperm
Classification • “White Oak” or Quercus alba • KINGDOM—Plantae • DIVISION—Magnoliophyta (Angiosperms) • CLASS—Magnoliopsida (Dicotyledons) • ORDER—Fagales • FAMILY—Fagaceae • GENUS—Quercus • SPECIFIC EPITHET—alba
Why Are Plants Important? • 1. With a partner, list five items you use daily that are byproducts of plants. • 2. With your partner, list three items that plants must get from animals—either directly or indirectly. • 3. Using your answers to questions 1 and 2, construct a diagram that illustrates the interdependence of plants and animals.
Plants are essential to our survival! • How? • Food • Clothing • Medicine • Construction • Even things you don’t think about… • Silk? This comes from an animal right? The silkworm. • But… did you know? • Even animal products that we use can be linked to plants. The example easily could have been a wool tie since sheep eat grass. But I thought I would challenge you a little with silkworms—they eat mulberry leaves.