Parts of Plants and their Functions

1. Parts of Plants and their Functions

2. Objectives • Note contributions of plants to the life cycle on earth • List and describe the purpose of the four main parts of plants • Explain process of photosynthesis • Explain process of respiration • Explain major structural differences between dicot and monocot stems • Describe process of pollination

3. Importance of Plants • Without plants, life on earth would not exist • Plants are the source of food for humans and animals, directly or indirectly • Plants produce oxygen and are the major producers • Plants help keep us cool, renew the air, slow wind, hold soil in place, shelter wildlife, beautify space, perfume the air, furnish building materials, and fuel

4. ROOTS

5. Root Functions • Anchor the plant and hold upright • Absorb water and minerals from the soil and conduct them to the stem • Store large quantities of plant food • Propagate or reproduce some plants • The first three are essential to all plants

6. Root Structure • The internal structure of a root is similar to a stem • Older roots of shrubs and trees have a phloem on the outside, a cambium layer, and xylem (wood) on the inside • A phloem is the old outer layers of corklike bark

7. The phloem carries manufactured food down to the root for food and storage • The xylem carries water and minerals up to the stem

8. External structures of roots are different form stems • Roots have a root cap that produce new cells which lubricate a path and protect the cap as new roots push its way through the soil

9. Behind the root cap are many root hairs which absorb moisture and minerals for larger roots and the stem • Side roots of increasing size form as the plant grows older

10. Roots are important agricultural cash crops • Carrots, beets, radishes and sweet potatoes are roots • Roots also serve for propagation • Dahlia, peony, and sweet potato have tuberous root clumps that can be separated will sprout new roots and plants

11. Fibrous Roots • Fibrous root plants are very easy to transplant • Roots are smaller, shorter and more compact, allowing more roots to be saved

12. Tap Roots • Tap root systems have longer and fewer roots • Tap roots are usually cut off during transplanting which loses root hairs and the ability absorb water and nutrients • Tap roots will conduct and store water and nutrients but not absorb it

13. Roots will move toward moisture in the soil • Central roots grow downward because of the force of gravity • This is know as geotropism and is controlled by the root tip

15. Types of Stems • Herbaceous – soft tissue that bends (ex: houseplants) • Woody – brittle, non-bendable, bark-like tissue (ex: trees, shrubs)

16. Functions of Stems • Transport materials up and down the plant through the vascular system • Consists of xylem and phloem tissue • Herbaceous stems have vascular bundles, which consist of both xylem and phloem • Woody stems have a vascular cylinder in which the outer portion is the phloem and the inner portion is the xylem

17. Herbaceous Stem Woody Stem

18. Xylem Tissue • Moves water and nutrients UPward from the roots to the stems and leaves Phloem Tissue • Moves water and nutrients DOWNward from the stems and leaves to the roots

19. Other Functions of Stems • Provide physical support for leaves, flowers, and fruit • Store food (ex: onions, garlic, potatoes) • Green stems have chlorophyll in them and conduct minor photosynthesis • Capable of reproduction • Help establish tendrils which aid climbing plants

21. Underground stem that grows horizontally Ex: Iris, Ginger Enlarged stem that grows underground Ex: Potato Threadlike leafless growth on a stem that attaches itself to other stems/objects Ex: Sweet pea Above ground stem that grows horizontally Ex: Strawberry Underground food storage consisting of flat, fleshy leaves with roots on lower side Ex: Onion Food storage structure at the end of a stem that grows underground Ex: Gladiolus

22. Leaves

23. The Plant Body: Leaves • FUNCTION OF LEAVES • Leaves are the solar energy and CO2 collectors of plants. • In some plants, leaves have become adapted for specialized functions.

24. EXTERNAL ANATOMY • Leaves possess a blade or lamina, an edge called the margin of the leaf, the veins (vascular bundles), a petiole, and two appendages at the base of the petiole called the stipules.

25. EXTERNAL ANATOMY

26. Phyllotaxy - Arrangement of leaves on a stem

27. Leaf types - Simple, compound, peltate and perfoliate • Simple leaf = undivided blade with a single axillary bud at the base of its petiole. • Peltate leaves = petioles that are attached to the middle of the blade; examples include mayapple • Perfoliate leaves = sessile leaves that surround and are pierced by stems; examples include yellow-wort and thoroughwort Yellow Wort Mayapple

28. Leaf types – Pinnately & Palmately Compound Leaves • Compound leaf = blade divided into leaflets, leaflets lack an axillary bud but each compound leaf has a single bud at the base of its petiole • pinnately-compound leaves: leaflets in pairs and attached along a central rachis; examples include ash, walnut, pecan, and rose. • palmately-compound leaves: leaflets attached at the same point at the end of the petiole; examples of plants with this leaf type include buckeye, horse chestnut, and shamrock.

29. Venation = arrangement of veins in a leaf • Netted-venation = one or a few prominent midveins from which smaller minor veins branch into a meshed network; common to dicots and some nonflowering plants. • Pinnately-veined leaves = main vein called midrib with secondary veins branching from it (e.g., elm). • Palmately-veined leaves = veins radiate out of base of blade (e.g., maple). • Parallel venation = characteristics of many monocots (e.g., grasses, cereal grains); veins are parallel to one another. • Dichotomous venation = no midrib or large veins; rather individual veins have a tendency to fork evenly from the base of the the blade to the opposite margin, creating a fan-shaped leaf (e.g., Gingko).  

30. Venation Types Netted or Reticulate Venation

31. Leaf – Internal Anatomy

32. Specialized or Modified Leaves • Cotyledons: embryonic or "seed" leaves. First leaves produced by a germinating seed, often contain a store of food to help the seedling become established. • Tendrils - blade of leaves or leaflets are reduced in size, allows plant to cling to other objects (e.g., sweet pea and garden peas. • Shade leaves = thinner, fewer hairs, larger to compensate for less light; often found in plants living in shaded areas. • Drought-resistant leaves = thick, sunken stomata, often reduced in size • In American cacti and African euphorbs, leaves are often reduced such that they serve as spine to discourage herbivory and reduce water loss; stems serve as the primary organ of photosynthesis. • In pine trees, the leaves are adapted to living in a dry environment too. Water is locked up as ice during significant portions of the year and therefore not available to the plant; pine leaves possess sunken stomata, thick cuticles, needle-like leaves, and a hypodermis, which is an extra cells just underneath the epidermis

33. Specialized or Modified Leaves • Prickles and thorns: epidermal outgrowths on stems and leaves (e.g., holly, rose, and raspberries; Hypodermic trichomes on stinging nettles. • Storage leaves succulent leaves retain water in large vacuoles. • Reproductive leaves, (e.g., Kalanchöe plantlets arise on margins of leaves. • Insect-trapping leaves: For example: pitcher plants, sundews, venus flytraps, and bladderworts have modified leaves for capturing insects; All these plants live under nutrient-poor conditions and digest insect bodies to obtain nitrogen and other essential nutrients. • Bracts:  petal-like leaves. • Window Leaves:  plant is buried in soil with transparent part exposed to light.  Being buried reduces loss of war in arid environments. • Flower pot leaves:  Structure to catch water and debris for nutrient collection - fairy-elephant's feet.

34. Cotyledons or “seed leaves”

35. Tendrils Garden Pea

36. Leaves as Needles and Spines

37. Leaves as Colorful Bracts

38. Flower Pot Leaves Fairy Elephant’s Foot

39. FLOWERS

40. Important Parts of a Flower • 4 main parts • Sepal • Petal • Pistil (or carpel) • Stamen

41. Sepals • Protect flower while developing from bud • Look like green little leaves • Collectively called CALYX

42. Petals • Member of COROLLA • All the petals make the corolla • Brightly colored part of a flower • Corolla and calyx make up perianth • Used to attract pollinators

43. Female Parts: PISTIL • Sits on the receptacle • Made of 4 parts: • Stigma • Style • Ovary • Ovule

45. Female Parts Continued • Stigma • Where pollen grains attach to • Style • Long filament structure • Prevents pollen contamination • Ovary • Protects ovule; becomes fruit when fertilized • Ovule • Becomes seed when fertilized

46. Male Parts: STAMEN • 3 parts • Anthers • Connective • Filament

47. STAMEN cont… • Anthers • Produce pollen • Contains thousands of pollen grains • Pollen contains male sex cells • Filament • Holds the anthers • Fine and hair like

49. Other Flower Parts • Receptacle • The part of the flower that holds everything together • Peduncle (pedicel) • Stalk of the flower

50. Types of Flowers • Imperfect • Perfect • Complete • Incomplete