Introduction to Horticulture

1. Introduction to Horticulture By Carrie Carson

2. The Importance of Plants • Without plants, life on earth could not exist • Plants are the primary source of food for humans and animals

3. The Importance of Plants cont. • Plants also: • Provide oxygen • Provide shade • Supply us with medicines • Renew the air • Slow down the wind • Hold soil in place • Are a home for wildlife • Furnish building materials and fuel

4. Parts of the Plant • Most plants are made up of four basic parts: • Leaves • Stems • Roots • Flowers (these later become fruit or seeds)

5. Are the food factory of the plant They produce all of the food that is used by the plant and stored for later use by the plant or by animals Leaves

6. Leaves Come in All Shapes and Sizes! • Needles are actually very narrow leaves • The thorns on a cactus are leaves • Some leaves are flat • Other leaves, like onion leaves, are cylindrical • The shape and size of leaves helps to identify plants

9. Leaves are arranged in many different patterns and positions: Alternate Opposite Whorled Simple Pinnate Bi-Pinnate Palmate Leaf Arrangement

10. Leaves on the Outside • Parts: - Petiole - Blade - Vein - Midrib - Margin Tip Margin Midrib

11. Leaf Parts cont. • Petiole - leaf stalk • Blade - the larger, usually flat part of the leaf • Midrib - large central vein from which all other leaf veins extend • Veins - form the structural framework • Margins - edges of plant leaves

12. Leaves on the Inside • Leaves have specialized cells that perform very important, very specific tasks.

13. Epidermis - skin of the leaf Single layer of cells Chief function: protect the leaf from loosing too much moisture Guard Cells - open and close a small space or pore on the underside of a leaf called a stoma to allow the leaf to breathe (exchange O2 for CO2) and transpire (or give off moisture) Leaf Cells

14. Leaf Cells cont. • Chloroplasts • Food making cells • Chlorophyll - green color • Photosynthesis • Process by which chloroplasts make food • The oxygen created is used directly by people and animals • Without O2 there would be no burning, rusting, or rotting

15. Photosynthesis 6H2O + 6CO2 ----------> C6H12O6+ 6O2 LIGHT Six molecules of water plus six molecules of carbon dioxide in the presence of light produce one molecule of sugar plus six molecules of oxygen

16. Plant Food • Food made in the leaves moves down the stem to the roots • It is then used by the plant or stored in the roots or stem as sugar, starch, or protein • The plant is also used as food for people and animals • The leaves are usually the most nutritious part

17. Plants breathe 24/7 They consume O2 and release CO2 Roots, stems, and leaves all need O2 to grow Plants produce more O2 during photosynthesis than they consume while breathing Respiration

18. Stems have 2 main functions: The movement of materials Movement of water and minerals from roots up towards the leaves Movement of manufactured food from the leaves down to the roots Support of the leaves and reproductive structures Flowers and fruit or seeds Stems

19. Stems cont. • Stems are also used for: • Food storage • Irish Potato • Reproductive methods • Stem cuttings or grafting • Green stems manufacture food just like leaves

20. Stems on the Outside • Lenticels • Breathing pores

21. Stems on the Outside cont. • Bud scale scars • Indicate where a terminal bud has been located • The distance between two scars represents one year of growth • Leaf scars • Show where leaves were attached

22. Unique Stems • Irish Potato & Gladiolus • Very different stems • Stems are used for food storage and plant reproduction

23. Stems on the Inside • In all stems: • Water and minerals travel up the XYLEM • Manufactured food travels down the PHLOEM

24. Dicots • Dicots (2 cotyledons) the xylem and phloem are separated by the cambium • The cambium produces new cells • Grow continually because the cambium builds new xylem and phloem cells • Trees are a perfect example! • Sap = new xylem • Heartwood = old, inactive xylem • Tree bark = old, inactive phloem

26. Monocots • One cotyledon (seed leaf) • Grasses, corn • No outside cambium • Vascular bundles that contain xylem & phloem • Cells don’t increase in number, they grow in size (won’t keep growing like a tree)

28. Monocots vs. Dicots

29. What do we do with Stems? • Food • Asparagus • Irish Potato • Celery • Building Materials • Wood

30. Roots • Usually underground – not visible • Functions: • Anchor the plant and hold it upright* • Absorb water and minerals from the soil & conduct them to the stem* • Store large quantities of plant food* • Propagate or reproduce in some plants * = essential to all plants

31. Very similar to a stem Older roots of shrubs & trees have: Phloem on the outside (old phloem is bark) Cambium layer Xylem (wood) on the inside Roots on the Inside

32. Phloem • Carries manufactured food down to the root for food storage • Xylem • Carries water and minerals up to the stem

33. Roots on the Outside • Different from a stem • On a stem, the terminal bud initiates growth • On a root, the root cap initiates growth • Root cap continuously makes new cells that protect the root as it pushes into the soil

34. Root External Structure • Behind the root cap are root hairs • Root hairs become side roots that branch out as the root grows older • Absorb moisture and minerals which are conducted up to the larger roots and the stem

35. Roots as Crops • Cash crops • Carrots • Beets • Sugar Beets - Sugar • Radishes • Sweet Potatoes

36. Root Propagation • Plants with tuberous roots: • Dahlia • Peony • Sweet Potato • Are propagated by separating the root clump or by rooting spouts from the root

37. Types of Root Systems Fibrous Root System vs. Tap Root System

38. Which root system is easier to transplant? Fibrous roots or tap roots? Answer: Fibrous roots Why? Because when plants are dug up out of the ground, a greater % of the fibrous roots system is saved.

39. If a root loses to many root hairs while being transplanted, the plant will die. Larger roots only conduct & store water, nutrients, and food Root hairs absorb moisture from the ground

40. Flowers, Fruits, & Seeds • Flowers are pretty & contain nectar in order to attract insects • These insects fertilize the flower by pollination • Pollination begins fruit and seed formation

41. Fruits & Seeds • Fruits and seeds are eaten, collected, and spread out by animals and people • This reproduces the plant

42. Seeds • Seeds have special devices to ensure propagation • Some seeds are sticky (thistles), some float in the wind (dandelions), others can survive stomach acid (cherry pits)

43. Flower Parts • Flowers differ in shape, size, and color, but all have relatively the same parts

44. Flower Parts cont. • Seeds are the most common way plants reproduce in nature • Sexual process involving male and female parents • A complete flower has both male and female parts • Only one parent is needed if a plant is self-fruitful, or can pollinate itself

45. Flower Parts cont. • 4 main parts • Sepals • Petals • Stamens • Pistil

46. Green, leaf like parts of the flower that cover and protect the flower bud before it is open The Sepals

47. Petals • Are actually leaves • Generally the most striking part of the flower • Bright colors are used to attract insects for pollination

48. The Stamens • Male reproductive part • Each stamen consists of: • Filament • Anther – contains the pollen (male sex cell)

49. Located in the center of the flower Female part Produces female sex cells (eggs or ovules) If fertilized, the eggs become seeds The Pistil

50. 3 main parts: Stigma – sticky, catches the pollen Style – tube that leads to the ovary Ovary – eggs develop here, after fertilization the ovary grows to become a fruit or seed coat Parts of the Pistil