Basic Botany, Plant Physiology, and Environmental Effects on Plant Growth

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. Plant Parts and Functions Stems Leaves Buds Roots Flowers Fruit Seed Plant Development Photosynthesis Respiration Transpiration Environmental Factors Affecting Plant Growth Temperature Light Water Topics

4. Reproductive Flower Buds Flower Fruit Seeds Plant parts of sexual reproduction Vegetative Roots Stems Leaves Leaf Buds Often used in asexual reproduction (vegetative) Plant Parts

5. Principal Parts of a Vascular Plant

6. Stems support: 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 Stems

7. 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! Nodes and Buds

8. Proper Pruning Cut: Tree

9. Proper Pruning Cut: Cane

10. Plant Cuttings

11. Shoot 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 Types of Stems

12. 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? Types of Stems and Modifications

13. Above-Ground Stem Modifications Stolons and Crowns Spurs

14. Below-Ground Stem Development Rhizomes Tubers

15. Below-Ground Stem Development Corm Bulb

16. 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 Vascular Tissue:“The Plants Circulatory System”

17. “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? Arrangements of Vascular Tissue

18. Diagram of Vascular Tissue

19. 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” Life Span of a Stem

20. Leaves: Are attached to the stem by petioles 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 Leaves

21. Type of Leaves

22. Epidermis 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 Outer Leaf Structure

23. Mesophyll 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 Inner Leaf Structure

24. Structure of a Leaf Blade

25. Bracts

26. Tendrils

27. Cotyledons

28. 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 Leaf Shape and Plant Identification

29. Types of Leaf Veins

30. “Structure” Simple Compound Palmate Pinnate Double Pinnate Shape Blade Apex Base Margins Entire Serrate Crenate Dentate Ciliate Lacerate Sinuate Incised Lobed Cleft Leaf “Structure”, Shape, and Margins

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 along the stem 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 Leaf Arrangement

37. Leaf Arrangement

38. Leaf Arrangement (cont.)

39. 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 Buds

40. Principal Functions 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 Roots

41. Root Structure

42. Two types of Root Systems Tap 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 ? Root Systems

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. Sepals 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. Flower Parts

45. 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 Reproductive Flower Parts

46. Structure of a Generalized Flower

47. 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 Types of Flowers

48. Common Flower Inflorescences

49. Common Flower Inflorescences (cont.)

50. 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 What Is a Fruit?