Importance of Plants

1
Importance of Plants

• Plants define biomes
• Forest
• Prairie
• Desert
• Plants adapted to land before animals.
• Plants sustain animal life

2
Evolution of Plant Adaptation to Land

• 500M years
• Moss
• nourish embryo
• 430M years
• Ferns
• water nutrient transport
• 400M years
• Gymnosperms (pine)
• seeds in cones
• 200M years
• Angiosperms (flowers)
• attract pollinators
• fruit contain seed

3
Importance to Humans

• Food
• Wheat, rice, corn
• Fiber
• Cotton
• Feed
• Livestock
• Construction
• Lumber
• Energy
• Ethanol, E85, Biodiesel
• Health
• Aspirin (White Willow bark)
• Pyrethrum (chrysanthemum)
• Antibiotics

4
Asexual Reproduction in Plants

• Meristem Tissue
• All mitosis!
• Stolons aboveground stem
• strawberry
• Rhizomes underground stem, iris
• Tubers portion of rhizome,
• potato
• Corm underground stem, gladiolus
• Bulb modified leaf, onion
• Plantlets maternity plant
• Cuttings pineapple, sugarcane
• Grafting fruit trees, grapes

5
Cut Flower Market in U.S.

• Per Capita Consumption
• Switzerland 101.4 vs U.S. 25.9
• Top Cut Flower
• Rose
• U.S. Imports
• Columbia and Ecuador
• Cut Flower Purchases
• Florists 21.9
• Supermarkets 49.0

6
Death of a Cut Flower

• Flowers Strive to Reproduce
• Respiration increases ? heal wound
• Water uptake stops ? air blocks uptake
• Hydrating solution (Sprite?) for shipping
• Citric acid lowers pH ? faster water uptake
• Disinfectant ? protects flower
• Sugar (20) ? food source
• Cold storage ? slows respiration
• After 1 week
• Lower leaves lost first
• Scent production decreases
• Petals begin to shed

7
Types of Flowering Plants

• Monoecious
• male and female flowers
• on same plant
• Corn, oak, cucumber, watermelon
• Dioecious
• male and female flowers
• on separate plants
• honey locust, willow, holly, cannabis

8
Types of Flowering Plants
Monocotyledon (Monocot) 1 cotyledon (seed
leaf) Flower parts in 3s Parallel leaf
veins Eudicotyledon (Eudicot) 2 cotyledons
Flower parts in 4s or 5s Net leaf veins
9
Anatomy of a Flower
Flower have 4 whorls of modified leaves.
10
Anatomy of a Flower
Simple Fruits Single carpels Peas, beans,
corn Compound Fruits Fused
carpels Raspberry, strawberry

• F

Day Lilly
11
Alternation of Generation in Flowering Plants
Diploid (2n) Sporophyte plant you can
see Megasporocyte Microsporocyte
Meiosis Megaspores Microspores
Mitosis Female Gametophyte
Male Gametophyte Embryo Sac Pollen
Grain (egg) (sperm)
Haploid (1n) Gametophyte
multicelled gamete
12
Pollen Production

• Anther
• 4 Pollen Sacs (2N)
• Meiosis ? Microspores (1N)
• Mitosis ?
• tube cell
• generative cell
• Mitosis ? 2 sperm
• Pollen 3 celled Male
• Gametophyte

13
Egg Production

• Ovary Ovule (2N sporophyte)
• meiosis ? 4 spores
• Megaspores (1N)
• 1 of 4 survive
• mitosis ? 8 nuclei
• cytokinesis ? 7 cells
• embryo sac female gametophyte
• 3 antipodals
• 1 central cell with 2
• polar nuclei
• 2 synergids
• 1 egg

14
Pollination

• Pollen ? stigma
• Artificial
• Cross-pollination
• pollen from different plant
• Self-pollination
• pollen from same
• plant

15
Fertilization

• Pollen Grain
• lands on stigma
• germinates
• forms pollen tube
• grows between cells to the ovule.
• Double fertilization occurs.
• 1 sperm egg zygote (2N)
• 1 sperm 2 polar nuclei 3N endosperm cell.

16
Embryo Development

• Cell Division
• Zygote divides
• small cells ? embryo
• larger cells ? suspensor
• Cell elongation
• growth
• Differentiation
• tissue and organs
• Meristem
• Embryonic tissue
• Active cell division
• Root Tip
• Shoot Tip
• Lateral

17
Seed Germination

• Seed respiration and
• metabolism low
• Germination
• Embryo resumes normal growth and metabolism
• Dormant period
• Growing conditions
• Oxygen
• metabolism
• Adequate Temperature
• enzymes
• Adequate Moisture
• hydration
• Light
• stimuli

18
Monocot and Eudicot Seed
Corn
Bean
Endosperm (3n) provides nutrients to embryo.
Mainly starch.
Cotyledons (2n) feed embryo. Mainly oils and
protein
Liquid starch (coconut, sweetcorn) has cell wall
formation delayed.
19
Seed Dispersal

• Dispersal
• Wind
• Maple tree, dandelion
• Animal food
• cherries, tomatoes, apple
• Trapped on animals
• Cocklebur, clover
• Plant Domestication
• Goes against natural selection for survival of
  the fittest.