1. Life of a Flowering Plant
Chapter 20
Life of a Flowering Plant

2. 20.1 Reproductive Adaptations
Flower is a specialized shoot with modified leaves
sepals: outermost ring; covers flower bud
petals: second ring; colorful to attract pollinators
stamens and carpels: center ring; reproductive structures

3. Reproductive Structures
Male
Gametophytes produced in stamens
anther: sac on top of stalk of stamen
Spores develop into pollen grains
Pollen = 2 cells with protective wall
Female
Gametophytes produced in carpels
Ovary at base
Ovules produce 4 cells each; 3 die
Each undergo 3 cycles of mitosis
embryo sac: resulting gametophyte
style: leads to ovary
stigma: sticky tip

4. Pollination
pollination: pollen grains released from anthers land on stigma
Pollen grain absorbs water and extends a pollen tube which grows toward ovary
Pollen cell divides forming 2 sperm (n)
One fertilizes egg = zygote (2n) = embryo
The other fertilizes the central cell = (3n) endosperm

5. Seed Dispersal Fruits protect seeds and help disperse
Travel by sticking to animal’s fur (burr)
Fleshy fruit that attracts animals; seeds are passed through digestive system
Water; coconuts
Wind; puffy dandelion

6. Seed Development
Seed coat: outer layer around seed that protects embryo and endosperm
Miniature root and shoot
cotyledon: storage and
transfer of nutrients to embryo
Dicots = dicotyledon = 2
Monocots=
(mono)cotyledon
Embryo grows through a few
stages of mitosis and stops to be
dispersed (stage that you see in
fruit)

7. Seed Germination
germination: embryo grows when conditions are favorable
Soak up water
split seed
coat
trigger
metabolic
changes

8. Adaptations and Conditions
Protections for developing shoots
Hooked tip
Sheath covering
Seedling: young plant that has just emerged from the soil
Vary among species
Desert plants: after heavy rainfall
Harsh winters: only after long period of cold
Fire: clears other growth

9. Asexual Reproduction vegetative reproduction: asexual reproduction
Cacti; dropped shoots become new plant
Strawberries and grasses
send out runners
Some trees send out
shoots from underground
stems

10. Different Life Cycles Annuals: complete life cycle in one year
Biennials: 2 years, flower in second
Perennials: multiple times per year

11. 20.2 Plant Structure
Roots
fibrous root: mat of thin roots spread out below the soil surface
Increased surface area
grasses
taproot: one large vertical root with smaller branches
Starch-storing
Carrots

12. Shoots Stems, leaves, and flowers stems: support leaves and flowers
nodes: point where leaves and stems attach
internodes: portions of stem between nodes
Transport water and nutrients

13. buds: undeveloped shoots
Terminal bud: tip of stem
Axillary: in the angles of a leaf - branches
blade: main part of the leaf
Primary photosynthesis site
petiole: stalk that connects leaf to stem
veins: throughout leaves to carry water and nutrients
Some plants have modified leaves
Celery stalks are leaves; onion is underground shoot

14. Plant Tissues Dermal Vascular Ground
Meristematic: differentiates into the others

15. Dermal Tissue Outer covering or “skin”
Epidermis: tissue of nonwoody organs
One or more layers of cells
Covers and protects young parts
Secretes waxy cuticle
Periderm: older tissue

16. Vascular Tissue
Transports water, mineral nutrients, and organic molecules; structure
xylem: water and dissolved minerals
phloem: food; made in leaves and transported to parts that don’t photosynthesize

17. Ground Tissue Fills the spaces between dermal and vascular
Most of young nonwoody plant
Photosynthesis, stoage and support
cortex: ground tissue in a root

18. Leaf Structure

19. Types of Plant Cells
parenchyma: thin cell walls and large central vacuoles
Food storage
Photosynthesis and cellular respiration
Fruits
Phloem
collenchyma: unevenly thick cell walls
Grouped in strands or cylinders
Support to young parts
Young stems and petioles
sclerenchyma: specialized for support
Die and leave behind a “skeleton”
xylem

20. 20.3 Primary Growth Plants continue to grow their entire lives
meristems: tissues that differentiate into new dermal, vascular, and ground tissue
apical meristems: tips of roots and buds of shoots
Grow in length and branches
primary growth: growth in length

21. Primary Growth of Roots
root cap: tip of the root
Protects dividing cells of apical meristem
Apical meristem
Replaces cells of root cap
Produces cells for primary growth
Forms 3 cylinders of cells; dermal, ground, vascular
Cells elongate by taking up water

22. Primary Growth of Shoots
Apical meristem: tip of terminal bud
Elongation just below
Auxillary buds
Formed as elongating cells push upward
Cylinders of cells

23. 20.4 Secondary Growth Growth in plant width
Woody plants; vines, shrubs, trees
Vascular cambium and cork cambium
vascular cambium: cylinder of actively diving cells between xylem and phloem
Adds secondary vascular tissue to primary
Accumulates as wood

24. Cork cambium
cork cambium: meristem that develops from parenchyma cells
Produces tough outer layer of cork
Dead cork cells leave thick, waxy walls; protects and prevents water loss
bark: everything outside vascular cambium
Phloem, cork, cork cambium

25. Tree Rings Rings = yearly activity of vascular cambium
Spring; cells are larger and thinner
Cool and wet
Summer: cells are smaller and thicker
Hot and dry
Heartwood - dead xylem
Sapwood - xylem transports water