Kingdom Plantae
Lower Plants, Organization, Morphology and
Reproduction
Plant Evolution
Ancestor = Charophytes member of the green algae
Problems associated with movement to land
1. Desiccation (dehydration)
2. Gas exchange
3. Support of multicellular structures
4. Reproduction
5. Spore or seed dispersal
Alternation of Generations
Alternation of generations
Diploid• Full # chromosomes• 2n• All non-gamete
cells• Can’t be gametes• Human = 46
• Haploid• ½ # chromosomes• n• Gametes• At fertilization
become diploid zygote
• Human = 23
Alternation of generations
Two Generations:
1. Sporophyte stage (spore-plant)a. Diploid stage (2n)
b. Produces haploid spores by meiosis
c. Spores grow into gametophyte containing male or female repro structures.
Alternation of Generations
Alternation of generations con’t.
Two Generations:
2. Gametophyte (n) (gamete plant)
a. haploid stage
b. Male: has antheridia, makes sperm
c. Female: has archegonia, makes eggs
d. gametes produced via MITOSIS
e. Sperm swim
f. Fertilization produces zygote
g. Grows into Sporophyte
Alternation of Generations
Bryophytes(nonvascular land plants)
Hepatophyta
Liverworts
Anthocerophyta
Hornworts
Bryophyta
Mosses
The Hornworts (Anthocerophyta)
Anthoceros sp.
Moss plants – Bryophyta
gametophyte & sporophyte generations
See fig 27.12, Russell*
Adaptation to Land Problems associated with movement to land
1. Desiccation (dehydration)
2. Gas exchange
3. Support of multicellular structures
4. Reproduction
5. Spore or seed dispersal
Adaptation to Land (desiccation, gas xchge)
1. Stomata:
a. Openings in leaf surface
b. control H2O loss
b. allow for gas exchange
Adaptation to Land (desiccation,transport)
1. Stomata:
2. Vascular Structures
a. Xylem-H2O up from Roots
b. Phloem-sugar around
Adaptation to Land (dessication)
1. Stomata:
2. Vascular
3. Cuticle
a. H2O proof
b. prevents dessication
Cuticle(made of cutin)
Adaptation to Land (support)
1. Stomata: 2. Vascular Structures3. Support
a. Lignin in cell wallsb. allows for branching and larger size
BryophytesNo true roots or vascular tissue
- 2 cm tall
Still have a need for water (Repro)
Vascular PlantsDominant stage = sporophyte
(Gametophyte hidden)
Specialized organsa. Roots
- rhizomes
b. Stems
c. Leaves
Vascular plants con’t.
Branching
Some contain lignin
a. structural support
Vascular tissues
a. Xylem
b. phloem
Vascular Bundles inMonocot stem
Vascular plants con’t.Two types of growth – apical meristem
a. Primary growth
b. Secondary growth
Sperm still flagellated
Maintained stomata & cuticle
NonseedVascular
Plants
Lycophyta Psilotophyta Sphenophyta Pterophyta
Lycophyta Psilotophyta
Lycopodium sp. Psilotum sp.
(microphylls) (stems only)
Sphenophyta Pterophyta – the ferns
Equisetum sp.
Sori on the underside of sporophylls
Vascular Seed Plants
Coniferophyta- the gymnosperms
Anthophyta- the angiosperms
Seed plants
Purpose of the seed:
A. means of dispersal of offspring
B. Survive unfavorable conditions
C. Stores food for embryo
D. Protection from predatorsE. Remember “Seedy Side of Plants”
Seed plants (con’t.)
Non-flagellated sperma. pollen
b. Moved by water, wind, insects, and animals
c. Forms pollen tube for sperm
Egg cellsa. Called ovules located inside the
ovary
Seed plants con’t.
Reduced gametophyte
a. composed only of sperm or egg
Maintained:
a.vascular tissue,
b.Cuticle
c.stomata
Gymnosperms
A. Needle-like leaves
B. Found in moderately cold & dry regions
C. Direct pollination ovules NOT enclosed by tissue of the sporophyte (gym= naked)
Gymnosperm Life Cycle
Gymnosperms – naked seed plants
Cycads (Sego palm) Ginkgo biloba
Strobili: sporophylls (leaves with sporangia)
Phy: GinkophytaPhy: Cycadophyta
Welwitschia Ephedra
Phylum: Gnetophyta
Coniferophyta
Angiosperms
1. Produce flowers, seeds and fruit
2. Petals brightly colored to attract pollinators
3. Dominate the landscape
The anatomy of a flower
Flower anatomy con’t.
Angiosperms con’t.
Pollination1. Pollen grain lands on stigma and
germinates2. Pollen tube grows down through
style into ovary releases sperm into ovules (egg cells)
3. Mature ovary = fruit4. Mature ovule = seed
Pollination
Monocots vs. Dicots
Mono Dicot
1. 1 cotyledon 2 cotyledons
2. Parallel vein net-like vein
3. Fibrous root tap root
4. Flwr parts in 3 flwr parts in 4-5
5. Scattered bundles bundles in ring(in the stem)
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