Basic Botany and Plant Physiology

1. Basic Botany and Plant Physiology Written By Latif Lighari, Ph.D Cooperative Extension Program Tennessee State University Modified for Master Gardener training & Presented by Karla Kean, UT/Montgomery County Extension Agent

2. What is Botany? • Botanyis the study of plants. • An understanding of basic botany, plant physiology and the environmental factors that affect plant growth can help one gain practical knowledge of horticulture.

3. OUTLINE • Introduction • Plant Parts and Functions • Plant Growth and Development • Environmental factors affecting plant growth.

4. INTRODUCTION • All flowering plants have certain structure and functions in common. • There are also common responses to environmental conditions. • This unit looks at what most plants have in common, some differences between plants, and applies this information to practical gardening.

5. INTRODUCTION Non-vascular Plants vs. Vascular Plants • Primitive, non-vascular plants, such as liverworts and mosses lack conductive tissue for the circulation of water and nutrients, and are thus confined to a moist environment. • Their small size and relatively dull appearance render them of limited value in the landscape. • Vascular plants, which include both flowering and non-flowering plants, are very diverse. • The adaptability of their root and shoot systems have enabled them to establish and thrive in many habitats.

6. PLANT PARTS AND FUNCTIONS • Stems • Leaves • Buds • Roots • Flowers • Fruit • Seeds

7. PRINCIPLE PARTS OF A VASCULAR PLANT

8. PRINCIPLE PARTS OF A VASCULAR PLANT • Think of these parts as divided into two groups: reproductive and vegetative. • Reproductive parts include flower buds, flowers, fruit and seed. • Vegetative parts include roots, stems, leaves and leaf buds. • Many vegetative parts are used in asexual or vegetative reproduction such as cuttings, grafting, layering, etc.

9. STEMS • Support buds, flowers and leaves. • Transport water, minerals and sugars through the plant. • The points where leaves develop along the stem are called nodes. • Area between the two nodes is called an internode.

10. STEMS • The length of an internode depends on many factors: • Vigorous growing, healthy plants tend to have longer internodes than less vigorous plants. • Reduced light intensity in areas of high foliage density may increase internode length.

11. STEMS • So, what does this mean to the gardener? • Many plants root more easily at the nodes and some root only at the nodes. • Short, stocky transplants are more likely to develop when plants grow in strong light, have adequate spacing, and are only moderately fertilized.

12. TYPES OF STEMS • A Shootis a young stem with leaves present. • ATwig is a stem which is less that one year old and has no leaves, since it is in the winter dormant stage. • A Branch is a stem which is more than one year old, and typically has lateral stems. • A Trunk is a main stem of a woody plant. Trees typically have a single trunk, but shrubs often have multiple trunks. • Vines produce long trailing stems that are sometimes able to support themselves by winding around or attaching to another plant or structure. • Canes are stems that usually live only a year or two. Plants with canes include rose, grape, blackberry and raspberry.

13. INTERNAL STEM STRUCTURE • Stems generally consist of several different types of tissue: • Xylem: conducts water, nutrients, and minerals from the roots to upper areas of a plant and generally forms the wood of woody plants. • Phloem: comprises much of the bark of woody plants and conducts sugars from leaves to growing points, fruits and storage areas.

14. INTERNAL STEM STRUCTURE • Cambium: is a meristem tissue; a site of cell division and active growth. It is located between the xylem & phloem and is responsible for diameter growth. The apicalmeristem is responsible for stem elongation. • Because xylem & phloem conduct water, nutrients, and manufactured substances throughout the plant, they are called vascular tissues.

15. There are two distinct arrangements of vascular tissue: Dicots and Monocots. Dicots: Have vascular tissue arranged in rings as found in most trees Monocots: Have veins arranged in bundles Corn is a typical monocot as are grasses, orchids, lilies and palms. INTERNAL STEM STRUCTURE

16. INTERNAL STEM STRUCTURE • Most, if not all monocots lack cambium tissue between xylem & phloem tissues. This means that a mature monocot stem does not increase much in diameter. • Dicots continue to increase in diameter throughout their lives.

17. INTERNAL STEM STRUCTURE • With this knowledge of stem structure, one can understand how a rodent chewing the bark off a tree kills the tree. • This information is also essential in grafting. Since only the cambium layer produces new xylem and phloem, the cambium layer of both plants must be exactly aligned if a graft is to grow.

18. MONOCOTS

19. DICOTS

20. STEM LIFE SPAN • Plants are sometimes classified by how long they live. • Annuals: produce seed, and die within a single growing season. (cantaloupe, corn, marigold etc.) • Biennials: produce vegetative structure and food storage organs the first growing season. The second season they flower, fruit, develop seed and then die. (carrots, cabbage, hollyhocks etc.)

21. STEM LIFE SPAN • Perennials: live three or more years. • Woody Perennials: have shoots & roots which survive many years, such as many trees & shrubs. • Herbaceous Perennials: have shoots which die back to the ground each year like hardy hibiscus, lilies, and many wildflowers.

22. LEAVES • Leaves are the primary organs to manufacture food for plants (like a factory). • Leaves can be narrow-leaves like pine needles or broad-leaves, like all other plants • The enormous diversity of leaf shapes, sizes, forms and arrangements is the result of plants adapting to conditions in a vast range of habitats.

23. LEAVES Leaves generally consist of: • Leaf Blade • Midrib • Smaller veins • Petiole – a branch holding the leaf

24. LEAVES • The principle function of a leaf is to manufacture plant sugars in a process called photosynthesis (which we will discuss a bit later). An important component of photosynthesis is light. • Typically, flattened leaf blades present a large area for efficient absorption of light. The vein system conducts water, sugars & other items through the leaf.

25. LEAVES • The greatest division within leaf types lies between deciduous and evergreen foliage in trees and shrubs. • Evergreen leaves are shed and replaced throughout the year. • Deciduous leaves are all replaced annually, mostly falling in autumn to minimize moisture loss in winter.

26. LEAVES • The leaf blade is comprised of several layers as illustrated. • The primary function of the epidermis is to protect the inner tissues.

27. LEAF SHAPE & VEIN ARRANGMENT • The term venation refers to the vein pattern in the leaf blade.

28. LEAF SHAPE & VEIN ARRANGMENT • Leaves may be simple or compound in arrangement: • Simple leaves consist of a single blade • Compound leaves have more than one blade. • Compound leaves may be palmately compound like horse chestnut, pinnately compound like a locust, or even double pinnately compound like the Kentucky Coffee Tree.

29. LEAF SHAPE & VEIN ARRANGMENT

30. LEAF ARRANGMENT • Leaf arrangement is another characteristic which helps identify plants. • Opposite leaves are positioned exactly across the stem from each other, with two leaves at each node. • Maple, ash, dogwood • Alternate leaves are arranged in steps or spiraled along the stem. • Oak, willow, sycamore • Whorled leaves are found in circles around the stem with 3 or more at a node. • Catalpa

31. LEAF ARRANGMENT

32. BUDS • Buds grow at nodes and tips of the stem • A bud is a condensed form of shoot which leaves or flower parts develop. • There are two types of buds: • Terminal Bud • Axillary or Lateral Bud

33. TERMINAL BUD

34. AXILLARY/LATERAL BUD

35. BUDS • Axillary buds may grow into lateral branches, so when pruning it is important to make pruning cuts just above an axillary bud. • It is also important that the axillary bud just below a pruning cut point in the direction you want the plant to grow, whenever possible. • This bud will be the strongest new growing point and will grow in the direction it points.

36. BUDS

37. BUDS • The terminal bud of many plants produces a chemical called auxin which inhibits the growth of nearby lateral or axillary buds. • This is referred to as apical dominance. If the terminal bud is removed, several lateral buds may quickly begin to grow. • The strongest growing bud is frequently the one nearest the end of the pruned stem. • Keep this in mind when pruning….

38. ROOTS • Absorb moisture and nutrients for the entire plant, but their functions go beyond this: • Transport moisture and nutrients to the base of the stem. • Anchor the plant, provide it with physical support and serve as food storage organs. • In some plants, roots may be used for propagation and as food

39. PARTS OF A ROOT • Root Cap • Root Hair • Root Body

40. FLOWER • Flowers are usually the showiest part of the plant and their function is sexual reproduction. • The bright color & fragrance attracts pollinators, usually insects, as well as gardeners. • Since the scientific name of plants is based on flower structure, knowledge of flowers is essential to plant identification.

41. PARTS OF A FLOWER • Sepals (Calyx) • Petals (Corolla) • Stamen –Anther & Filament (male part) • Pistil –Stigma,style and ovary (female part)

42. TYPES OF FLOWERS • A flower having all four parts, sepals, petals, pistil & stamens is called a complete flower. • If one or more of these parts is missing, the flower is designated incomplete. • Flowers containing functional stamens & pistils are called perfect flowers such as peaches or tomatoes. If either of these parts are lacking, the flower is imperfect.

43. FLOWERING PATTERNS • Peaches & tomatoes are examples of perfect flowers. • Insects, wind or contact transfers pollen from the anthers to the stigma which pollinates the flower. • The pollen grows, fertilization occurs and seed develops. These plants are self pollinated.

44. FLOWERING PATTERNS • Other plants, such as apples & pears, require pollen from a genetically different plant for fertilization to occur even if they have perfect flowers. • They must be cross-pollinated, usually by wind or insects.

45. FLOWERING PATTERNS • Monoecious plants have flowers with male parts (staminate) and female parts (pistillate) located separately on the same plant. • Corn, nut trees, vine crops such as cucumber, squash etc. • Dioecious plants are those which produce only male or only female flowers. • Holly, ginkgo, honey locust

46. MALE & FEMALE FLOWERS ZUCCHINI CUCURBITS

47. COMMON FLOWER INFLORESCENCES

48. FRUITS • Fruit consists of fertilized and mature ovules called seeds and the ovary wall. • Botanically, tomatoes are a fruit as are squash, cucumber, eggplant and beans. • The ovary wall may be fleshy as in peach or dry and hard as maple fruit and walnuts.

49. FRUITS • The edible portion of cantaloupe and other fleshy fruit is not affected by the pollen source. • The pollen source is only significant when the seed is saved or eaten. • Corn is an example. • Cantaloupe does not taste like cucumbers because of cross pollination.

50. TYPES OF FRUITS: • Fruits can be classified as: • Simple Fruit: develop from a single ovary, such as cherries, peaches, apples, tomatoes, nuts, maple seed and poppies. • Compound or Aggregate Fruits: develop from single flowers with many ovaries; most berries are aggregate fruits.