Download presentation
Presentation is loading. Please wait.
1
Basic Botany, Plant Physiology, and Environmental Effects on Plant Growth
The University of Tennessee Master Gardener Program Updated January 2002
2
Objectives To develop a basic understanding of:
Botany Plant Physiology Environmental Factors that affect Plant Growth To apply this basic understanding to home gardening.
3
Topics Plant Parts and Functions Plant Development
Stems Leaves Buds Roots Flowers Fruit Seed Plant Development Photosynthesis Respiration Transpiration Environmental Factors Affecting Plant Growth Temperature Light Water
4
Plant Parts Reproductive Plant parts of sexual reproduction Vegetative
Flower Buds Flower Fruit Seeds Plant parts of sexual reproduction Vegetative Roots Stems Leaves Leaf Buds Often used in asexual reproduction (vegetative)
5
Principal Parts of a Vascular Plant
6
Stems Stems support: Stems transport: Nodes Buds
Flowers Leaves Stems transport: Water Minerals Sugars Nodes The points where leaves develop along a stem Regions of high cellular activity The distance between nodes (internode) is affected by: Light (etiolation) Water Nutrients (N and micros) Genetics
7
Nodes and Buds Many plants develop one or more buds at the nodes (axillary buds) Axillary buds may grow into lateral branches When pruning a plant it is very important to make cuts just above axillary buds: Axillary buds grow Wound heals quickly When making cuttings, they should be made just below a node: Many plants root more easily at nodes, some only at nodes. Managing light, water, nutrients, and genetics are important to healthy transplant production!
8
Proper Pruning Cut: Tree
9
Proper Pruning Cut: Cane
10
Plant Cuttings
11
Types of Stems Shoot Twig Branch Trunk Vines
A young stem with leaves present Twig A stem less than 1 year old with no leaves present (dormant) Branch A stem more than 1 year old, with lateral buds Trunk A main stem of a woody plant Trees generally have a single trunk Shrubs often have 2 or more trunks Vines A long trailing stem that is able to support itself by winding around other plants
12
Types of Stems and Modifications
Canes A stem that lives only a year or two Contain a large amount pith (soft tissue) in the center Stem modifications Above-Ground Crowns Stolons Spurs Below-Ground Bulbs Corms Rhizomes Tubers All of these have buds or leaves present Can you think of examples of these structures?
13
Above-Ground Stem Modifications
Stolons and Crowns Spurs
14
Below-Ground Stem Development
Rhizomes Tubers
15
Below-Ground Stem Development
Corm Bulb
16
Vascular Tissue: “The Plants Circulatory System”
Xylem Transports water, nutrients, & minerals from roots to upper portions of the plant Forms the “wood” of woody plants Phloem Conducts sugars from leaves to growing points, fruits, & storage areas Comprises much of the bark of woody plants Cambium Cambium is the meristematic tissue (the site of cell division and growth) It is located between the xylem and phloem and produces both tissues Other meristematic tissue is found at the apical bud, where stem elongation takes place
17
Arrangements of Vascular Tissue
“Dicots” Vascular tissue form rings Woody plants “Monocots” Vascular tissue arranged in bundles Grasses, Orchids, Lilies Lack cambium tissue between xylem and phloem Stems of dicots tend to grow in diameter, while stems of monocots tend not to increase in diameter What does knowing about these tissues reveal to you about: Damage to the bark of a tree? Grafting?
18
Diagram of Vascular Tissue
19
Life Span of a Stem We often classify stems by how long they live:
Annual Produce seed and die within 1 year Biennials Produce vegetative structures and food storage organs the first year Reproduction takes place the second year and the plant dies When stressed, biennials can go through the entire process in 1 year (bolting) Perennials Live 3 or more years Usually produce flowers and seeds every year Herbaceous Perennial Shoots which die back to the ground every year “Biennial Perennials”
20
Leaves Leaves: Functions Are attached to the stem by petioles Petiole:
Consist of: Blade Midrib Smaller Veins Function To manufacture sugars in a process called photosynthesis Functions Petiole: Expands the leaf area and orients the leaf Blade: Provides a large area for the efficient absorption of light Midrib and Veins: Conducts water, sugar, and other compounds throughout the leaf
21
Type of Leaves
22
Outer Leaf Structure Epidermis Trichomes Cuticle Guard Cells Stomates
Outer protective layer Trichomes Extensions of epidermis that make leaves feel like velvet Cuticle Waxy layer (cutin) in some plants that protects plants from: Dehydration Penetration by some diseases Guard Cells Special epidermal cells that are capable of enlarging and contracting Stomates Openings that develop between enlarged guard cells Usually on the underneath side of the leaf Regulate the passage of water, oxygen, and carbon dioxide in and out of the leaf
23
Inner Leaf Structure Mesophyll Palisade Cells Parenchyma Layer
Where photosynthesis occurs Is comprised of 2 layers Palisade cells Parenchyma layer Palisade Cells Dense upper layers of the leaf Parenchyma Layer Lower spongy area with considerable air space Chloroplasts Actual site of photosynthesis Found in the palisade cells and the parenchyma layer Some plants vary leaf thickness with environmental conditions Special Leaves Bracts Tendrils Cotyledons
24
Structure of a Leaf Blade
25
Bracts
26
Tendrils
27
Cotyledons
28
Leaf Shape and Plant Identification
Leaves are one of the primary characteristics in plant identification Veining “Structure” Shape Margins Arrangement Leaf Veins Veins are the continuation of vascular tissue from the stem, through the petiole Veining Patterns Parallel Run parallel with length of the leaf Are connected by minute, straight veins Prominent in monocots Net Pinnate Palmate Prominent in dicots
29
Types of Leaf Veins
30
Leaf “Structure”, Shape, and Margins
Simple Compound Palmate Pinnate Double Pinnate Shape Blade Apex Base Margins Entire Serrate Crenate Dentate Ciliate Lacerate Sinuate Incised Lobed Cleft
31
Simple and Compound Leaf Types
32
Leaf Shapes
33
Common Leaf Shapes Acuminate: Tapering to a long, narrow point.
Acute: Ending in an acute angle, with a sharp but, not acuminate point. Obtuse: Tapering to a rounded edge. Sagittate: Arrowhead-shaped, with two pointed lower lobes. Truncate: Having a relatively square end.
34
Leaf Margins
35
Common Leaf Margins Entire: A smooth edge with no teeth or notches.
Serrate: Having small, sharp teeth pointed toward the apex. Dentate: Having teeth ending in an acute angle, pointing outward. Crenate: Having rounded teeth. Sinuate: Having a pronounced sinus or wavy margin. Incised: Margin cut into sharp, deep, irregular teeth or incisions. Lobed: Incisions extend less than halfway to the midrib. Cleft: Incisions extend more than halfway to the midrib.
36
Leaf Arrangement Uses of Leaves Leaf arrangement along the stem Food
Rosulate Basal leaves form a rosette Short internodes Opposite Two leaves exactly opposite Alternate Steps or spiraled Whorled Circles of three or more leaves Uses of Leaves Food Humans Animals Wild Livestock Ornamental Color Shape Soil Amendments
37
Leaf Arrangement
38
Leaf Arrangement (cont.)
39
Buds Buds are undeveloped shoots from which leaf or flower parts arise
Bud Scales Small, leathery, modified leaves that cover buds Bud Scale Scars Scars formed when the bud scales are removed Used in plant identification Types of Buds Terminal – dominant Auxin Lateral or axillary Adventitious May originate from internodes, leaves, or callus tissue of stems or roots Chilling Requirements Bud Use
40
Roots Principal Functions Parts or Zones of Growth Obvious
Absorb Water Nutrient Uptake Also Transport water and nutrients to the stem Anchor / Support Serve as storage organs Propagation Parts or Zones of Growth Merisematic Zone Where new cells are formed Root Cap – protects root tip Zone of Elongation Cells increase in size and push root Zone of Maturation Cells differentiate Root hairs form – short-lived, small roots - absorption
41
Root Structure
42
Root Systems Two types of Root Systems Uses Food Tap Fibrous Medicinal
Develops a main tap root with various amounts of lateral rooting Fibrous Develops small roots that spread out in a mat-like growth Uses Food Humans Fresh Processed Animals ? Medicinal Dried Fresh ?
43
Flowers Flowers are generally the showiest part of the plant, but they also serve a purpose Sexual Reproduction Color and / or Odor attracts pollinators (insects) Flowers are least influenced by environmental conditions; therefore they are important in plant identification.
44
Flower Parts Sepals Petals
Small, green leaf-like structures at the base of the flower that protect the flower bud Collectively – Calyx Petals Colored and aromatic part Collectively – Corolla The number of sepals and / or petals helps identify the family or genera Dicots generally have multiples of 4 or 5 Monocots generally have multiples of 3 Example Members of the “Rose” family have 5 petals and sepals.
45
Reproductive Flower Parts
Female Pistil (shaped like a bowling pin) Stigma (top) Style (middle) Ovary (bottom) Placenta Ovules – develop into seed after pollination Male Stamen (flowers often have a cluster of stamens around the pistil) Anther (pollen sac) Pollen is produced by the anther Filament (“stem”) supports the anther
46
Structure of a Generalized Flower
47
Types of Flowers Complete – all four parts Incomplete – lacks one part
Perfect – contains both function pistils and stamens Imperfect – lacks a functioning pistil or stamen Self-pollination Cross-pollination Monoecious – both male and female flowers on one plant Dioecious – contains only male or female flowers on a single plant
48
Common Flower Inflorescences
49
Common Flower Inflorescences (cont.)
50
What Is a Fruit? Something you eat for desert (not with the entrée)
Botanically, fruit is a ripened ovary Mature ovules (seeds) Ovary wall (flesh) Examples Tomatoes, cucumber, eggplant, beans Types of fruit Simple Single flower – tomato Aggregate (compound) Single flower with many ovaries – strawberry Multiple Tight cluster of many flowers – pineapple
51
Seed Structure Seed Growth Three Main Parts
Embryo – partially developed plant in a dormant state Radicle – embryonic stem Hypocotyl – stem Cotyledons – seed leaves Plumule – underdeveloped stem and leaves Endosperm – food source Seed Coat – protection from insects, diseases, and germination Seed Growth Germination – resumption of seed growth Moisture Oxygen Favorable temperature Light (sometimes)
52
Primary Parts of Common Seeds
53
Seed Germination and Storage
Most seeds require time after maturity before they will germinate. Others will require: Stratification Scarification Soaking Time, time, time! Storage Seeds are living things! They “live” longer when maintained in a cool and dry environment. Keep seed packets air tight (except beans ?) Store in a refrigerator or freezer
54
Plant Growth and Development
Three major processes Photosynthesis Respiration Transpiration
55
Photosynthesis Photosynthesis – “to put together with light”
Requirements: Light Carbon Dioxide Water Suitable Temperature Process – very complicated, but a simple description Carbon dioxide and water are combined using solar energy Simple sugars (glucose is formed and oxygen is give off (in the chloroplasts) Simple sugars are then converted into more complex sugars and starches; and stored All green tissue is capable of photosynthesis, but most takes place in the leaves What limits photosynthesis?
56
Respiration and Transpiration
Respiration is the “opposite” of photosynthesis Carbohydrates are broken down and the energy released is used for life processes As night-time temperatures increase, respiration increases Transpiration is the process by which plants loose water vapor 90% of the water entering a plant is transpired Water movement is important in moving nutrients, minerals, sugars, and other compounds; as well as maintaining turgor pressure and evaporative cooling
57
How a Plant Grows
58
Photosynthesis vs. Respiration
Produces sugars Stores energy Releases oxygen Uses water Uses carbon dioxide Occurs in sunlight Occurs in chloroplast Respiration Uses sugars for energy Release energy Uses oxygen Produces water Produces carbon dioxide Occurs in dark and light Occurs in all cells
59
Environmental Factors
Primary environmental influencing plant growth Temperature Light Water
60
Temperature Temperature is the main environmental factor affecting plant growth Germination Cool-Season vs. Warm-Season Hardiness Cold – Desiccation Heat Growth and fruit set Temperature influences quality!
61
Temperature and Germination
62
Light Three principal characteristics: Duration Quantity Quality
Intensity or brightness Phototropism Quality Color or wavelengths Red and blue light are most important Green is reflected by the plant Duration Photoperiod – amount of time a plant is exposed Short-Day Flower during long nights Mums and poinsettia Day-Neutral Not influenced by day length Ever-bearing strawberries Long-Day Flower during short nights Most summer plants
63
Light Management Not Enough! Too Much!
64
Water Water comprises most of all living things!
The plant is no different! Main component of protoplasm – the living part of the cell Water Acquisition Root hairs Vascular tissue Stomates Quality Low in salts Temperature Quantity Too much Diseases Too little Wilting Special structures Leaves
65
Water Management Too Much! Not Enough!
66
Questions?
Similar presentations
