Introduction to Plants

1
Introduction to Plants

• Mrs. M. Rightler

2
Earliest Plants

• Algae
• Phytoplankton
• Lived in the sea

3
Problems with life on land

• Problem
• Drying Out
• Making Food
• Reproduction
• Gravity Support
• Getting water nutrients

• Solution
• Waxy cuticle, stomata
• Formed leaves
• Develops spores seeds
• Bark (cork) vessels
• Roots vessels

4
Types of Plants

• Avascular
• Bryophytes
• nonseed plants
• Tracheophytes
• vessels for transport and support

5
Mosses Liverworts The Bryophytes

• First land plants
• AVASCULAR very small
• 500 m.y.a.
• Must grow in moist environments
• Used for fuel (peat)

6
Reproduction in Bryophytes

• Mosses have a protonema (liverworts do not)
• Sexual reproduction
• Antheridium makes sperm
• Archaegonium makes eggs
• Asexual reproduction
• Fragmentation
• Formation of gemmae

7
Tracheophytes

• Vessels
• XYLEM transports water dissolved minerals
  from roots to leaves
• PHLOEM transports sugars from leaves to rest of
  plant
• Spores or seeds for reproduction

8
Club Mosses (Lycophyta)

• Leaves produce spores
• Strobilus spore-bearing leaves
• Prothallus produces antheridia archaegonia

9
Horsetails (Sphenophyta)

• Jointed stems
• Reproduction similar to club moss

10
Ferns (Pterophyta)

• 400 m.y.a.
• Dominant form sporophyte
• Structure
• Rhizome underground stem
• Fronds leaves
• Sori store spores on underside of fronds

11
Gymnosperms

• Gymno naked Sperm seed
• First plants to produce seeds
• No flowers
• No fruit

12
Why Make Seeds?

• Has own food supply
• Protective coat against harsh conditions
• Some are designed for travel to new areas

13
Sporophytes produce

• MICROSPORE
• Produce male gametophyte
• Produce pollen
• MEGASPORE
• Produce female gametophyte
• Produce ovule (makes archaegonia with egg cells)

14
Gymnosperm Reproduction

• Pollen grains carried by wind
• Land on ovule, develop pollen tube
• Sperm move through tube to fertilize egg
• Fertilized egg ZYGOTE
• EMBRYO young, diploid sporophyte plant
• COTYLEDONS food storage for embryo, become
  first leaves

15
Why Pollen Instead of Spores?

• Plant can live in very dry areas
• Fertilization does not require water
• Pollen has protective coat and food supply for
  sperm

16
Why Ovules Instead of Archaegonia?

• Protective tissues prevent drying out
• Ovule holds archaegonia and protects eggs from
  elements

17
Minor Gymnosperm Groups

• Cycadophyta (1st in Triassic Era)
• Ginkgophyta
• Only one species today Ginkgo biloba
• Most lived 200 m.y.a.
• Gnetophyta only three genera
• Gnetum house plants
• Ephedra weight loss, allergies asthma
• Welwitschia

18
Coniferophyta (largest group)

• Needle or scale-like leaves
• Bear seeds in woody cones
• Can live in very cold climates
• Most are evergreens
• Have wood
• Made of thick-walled vessels (TRACHEIDS)
• Tracheids are xylem

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Angiosperms

• Angio flower Sperm seed
• Extremely diverse
• All have seeds enclosed in fruit

20
Cambium

• Any growth tissue in plants
• Types of cambium
• Vascular produces xylem phloem
• Cork produces cork (bark)

21
Overall Structures 121

• Roots
• Stems
• Leaves
• Flowers

22
Roots 124

• Absorb water nutrients
• Hold plant in place
• Root types
• Fibrous
• Tap
• Prop
• Aerial

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Stems 123

• Support leaves flowers
• Sometimes photosynthesis
• Transport (contain xylem phloem)
• Types
• herbaceous green flexible
• Woody stiff, have cork layer, usually brown

24
Leaves 119

• Cuticle protection
• Stomata gas exchange, water loss
  (transpiration)
• Epidermis protection, color
• Mesophyll
• Palisade most PHOTOSYNTHESIS
• Spongy Vascular bundles run through it

25
Flowers 131

• Pistils female reproductive structures
• Stamens male reproductive structures
• Complete flowers
• Have petals sepals
• Have male and female parts
• Incomplete flowers missing one or more parts

26
Types of Angiosperms 115

• Monocots
• mono one
• cot seed leaf
• Approx. 60,000 species
• Flowers multiples of 3
• Leaf veins parallel

• Dicots
• di two
• cot seed leaf
• Approx. 170,000 species
• Flowers multiples of 4 or 5
• Leaf veins branching

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Plant Tropisms

• Tropism plant response to external stimulus
• Positive plant moves toward stimulus
• Negative plant moves away from stimulus
• Types
• Phototropism light
• Gravitropism gravity
• Thigmotropism touch
• (nastic movement direction does not matter)

28
Plant Hormones

• Hormone chemical produced in one part of an
  organism that has an effect on a different part
  of the organism
• Types
• Auxins regulate growth
• Gibberellins speeds growth, germination
• Abscisic acid dormancy, close stomata, stress
• Ethylene ripens fruit