Basic Botany: An Introduction for Master Gardeners

Transcription

1 Basic Botany: An Introduction for Master Gardeners Dr. Robert Wyatt Professor of Botany and Ecology (retired) University of Georgia Importance of Plants Serve as primary food source Serve as fuel source Replenish oxygen supply Prevent soil erosion Cool the atmosphere Provide wildlife habitat Serve as drug source Beautify our surroundings Overview Plant taxonomy (names and classification) Plant life cycles (annual, biennial, perennial) Plant anatomy and morphology (internal and external structure) Plant vegetative (roots, stems, leaves) and reproductive (flowers, fruits, seeds) structures Plant physiology (photosynthesis, respiration, and transpiration) overview Some hands-on time with real plants! Plant Classification Kingdom Plant Division Magnoliophyta (flowering plants) Class Magnoliopsida (dicots) Order Magnoliales Family Magnoliaceae Genus Magnolia Species grandiflora Magnolia grandiflora L. (Southern Magnolia) M. grandiflora cv. Little Gem Rhododendron calendulaceum (Michaux) Torrey = Azalea calendulaceum Michaux Flame Azalea Lumpers vs. Splitters Latin Binomials vs. Common Names 1. One species many common names 2. One species no common name 3. Two or more species one common name 1page 1

2 Asclepias tuberosa Buckleya distichophylla Hexastylis shuttleworthii Asarum canadense Monocots vs. Dicots Zingiber officinale One seed leaf Leaves often parallel-veined Xylem and phloem paired in bundles, which are dispersed throughout stem Flower parts in 3s or multiples of 3 Two seed leaves Leaves usually netveined Xylem and phloem in a ring, with the xylem forming the inner ring Flower parts in 4s or 5s or multiples thereof 2page 1

3 Dutchman s Breeches Dicentra cucullaria Bleeding Heart Dicentra eximia Plant Life Cycles (1) Annuals complete their life cycle in one year or growing season (e.g., pansies, marigolds). (2) Biennials complete their life cycle in two years, typically dying after flowering in their second year (e.g., carrots, foxgloves). (3) Perennials live more than two years, often flowering many times. They can be herbaceous or woody (e.g., milkweeds, pines). Xanthorhiza simplicissima Most simply, yellow root! Monocarpic plants flower once, then die, whereas polycarpic plants flower many times in their life cycle (e.g., bamboos versus oaks). Internal Plant Parts Cells are the basic structural and physiological units of plants. Plant cells are unusual in retaining the capability to develop into a completely new plant. Tissues are large, organized groups of cells that work together to perform a specific function (e.g., xylem, phloem, meristems). External Plant Parts Organs are organized groups of tissues that work together to perform a specific function. These can be classified into two broad types: (1) Vegetative (roots, stems, and leaves) (2) Reproductive (flowers, fruits, and seeds) 3page 1

4 Plants are modular. Plant growth is indeterminate. Functions of Plant Roots (1) To absorb water and mineral nutrients (2) To anchor the plant in the soil (3) To support the stem (4) To store food Larch roots with mycorrhizae Acer negundo Box Elder Grass Fibrous roots Taproot 4page 1

5 Sweet Potato Ipomoea batatas Oak twig internode cluster of terminal buds axillary bud node 5page 1

6 Underground Storage Stems Irish Potato Solanum tuberosum rhizomes, bulbs, corms, and tubers Plant Growth Forms (1) Herbs are erect plants that die back to the ground at the end of the growing season. (2) Shrubs are erect plants with several main stems that persist aboveground and are < 12 feet tall. (3) Trees are erect plants with a single main stem (trunk) that persists aboveground and are >12 feet tall. (4) Vines and lianas are plants with long, trailing stems that may climb by various means. Squash Tendril Blade Petiole Lianas Stipules Tropical Rain Forest Liriodendron tulipifera Tulip Poplar Panama 6page 1

7 Lilac leaf cross-section blade Blade Alternate leaf arrangement 1 leaf/node Opposite leaf arrangement 2 leaves/node petiole axillary bud Stipule Chinese Chestnut 7page 1

8 Whorled leaf arrangement 3 or more leaves/node leaflet Catalpa speciosa Indian Cigar Tree node node Once pinnately compound leaf petiolule rachis node petiole axillary bud Twice pinnately compound leaf Palmately compound leaf leaflet rachis leaflet petiole petiole thorn axillary bud Horsechestnut Pinnately compound leaf Bitternut Hickory Palmately compund leaf 8page 1

9 pistil Dioecious Monoecious Myrica cerifera Bayberry or Wax Myrtle Determinate: Terminal flower opens first one pistil- one flower many pistils- one flower many flowers Indeterminate: Basal flower opens first 9page 1

10 Multiple fruit Pineapple Grape Pepo Berry Cucurbita pepo Pumpkin 10page 1

11 Pome Accessory fruit Legume English Pea Samara Sugar Maple Follicle Loculicidal Capsule Asclepias syriaca Common Milkweed Yucca Spanish Bayonet 11page 1

12 Achene Sunflower Seed = embryo + endosperm + seed coat oregonstate.edu/ mg/botany 12page 1