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Gymnosperms & Angiosperms
Lecture 9
Spring 2014
Vascular Plants: Seed Plants
1
What traits unite the
seed plants?
Fig. 29.7
Gymnosperm evolution
2
Gymnosperm evolution
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Adaptations of seed bearing vascular plants
• Heterospory
– (present in a few seedless vascular plants)
•
•
•
•
Reduced gametophytes
Pollen
Ovules
Seeds
Gymnosperm evolution: Heterospory
Heterospory
– Production of two different types of spores
Ch 29,
p.613
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5
Gymnosperm evolution: Reduced gametophytes
Fig. 30.2
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Gymnosperm evolution: Reduced gametophytes
Why is this beneficial?
Fig. 30.2
Gymnosperm evolution: Pollen
• Pollen grains
– Microsporangium
– Sporopollenin
• Benefit of pollen grains?
7
Gymnosperm Lifecycle
8
Female Gametophyte
produced inside ovule
Fig. 30.6
Male Gametophyte
(in Pollen)
Gymnosperm Lifecycle: Ovules
• Megasporangium
• Megaspore
• Integument = sporophyte tissue that envelopes and protects
the megasporangium
Fig. 30.3
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10
Gymnosperm Lifecycle
Fig. 30.6
Gymnosperm Lifecycle: Ovule
Fertilized Ovule
Fig. 30.3
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Gymnosperm Lifecycle: Seeds
Seed = embryo, food supply, and protective
coating
Benefits?
Fig. 30.3
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Gymnosperm Lifecycle: Seeds
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Gymnosperms
• Seeds not enclosed in a
chamber
gymnos = naked,
sperm = seed
Exposed seed
Enclosed seed
14
Gymnosperm diversity
4 phyla
• Phylum Coniferophyta
• Phylum Ginkgophyta
• Phylum Cycadophyta
• Phylum Gnetophyta
Phylum Coniferophyta
• ~600 species
• Pines, firs, larches,
hemlocks, cedars,
junipers, etc.
Doug fir
Juniper
Pine
Spruce
Larch
Port Orford cedar
True cedar
15
Phylum Coniferophyta
16
Tallest trees
Coastal redwood
(Sequoia
sempervirens)
As tall as 90 m
record 111.6 m
(366 ft) tall
Largest living organism - most
biomass
Giant sequoia (Sequoiadendron
Oldest living organism giganteum)
Bristlecone pine
General Sherman (not pictured)
(Pinus longaeva)
31 m(101.5 ft) in
4,600 years old still
circumference
living
2000-2500 years old
Phylum Coniferophyta
• Other adaptations
– Many evergreen
– Modified leaves
• Often needlelike
• Thick cuticle
• Xylem = tracheids
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Phylum Coniferophyta
• Seed cones vs. pollen
cones
Seed cones
(shore pine)
Pollen cones
(shore pine)
Seed cone
(fir tree)
Phylum Coniferophyta
Variations in seed
cones
Yew aril
Juniper “berry”
19
Phylum Ginkgophyta
1 living species = Ginkgo biloba
• Once widely distributed in
Northern Hemisphere
• Now exists only in cultivation
• Flagellated sperm
• Xylem = tracheids
• Ginkgo Petrified Forest
State Park
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Phylum Cycadophyta
~ 130 species
Cycads
• Found in tropics and
subtropics
• Single unbranched trunks
• Palm-like leaves
• Flagellated sperm
• Large cones
– 3 ft long, 100 lbs
• Xylem = tracheids
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Phylum Gnetophyta
~ 75 species
Welwitschia, Gnetum,
Ephedra
• Xylem = tracheids
and vessels
Welwitschia
Gnetum
Ephedra
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Major events in plant evolution
“Age of angiosperms”
• 140-125 mya angiosperms appear
• 65 mya major diversification
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Angiosperm evolution
~ 250,000 species
(90% of all plant
species)
Phylum Anthophyta
• All flowering plants
• Seeds enclosed in a
chamber to mature
Exposed seed
Enclosed seed
25
Angiosperm evolution
Adaptations of angiosperms
• Flowers
• Fruits
Fig. 30.3
Pedicel
26
Angiosperm Lifecycle
Male Gametophyte
(in Pollen)
Sporophyte
Female Gametophyte
(Embryo Sac) inside
ovule
Fig. 38.2
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Angiosperm Lifecycle
Fig. 38.3
Angiosperm Lifecycle
Fig. 38.3
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Angiosperm Lifecycle
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Fig.30.10
Angiosperm Lifecycle:
Double Fertilization
Fig. 38.6
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Angiosperm diversity
Fig. 30.12
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Angiosperm diversity
Basal Angiosperms
• Oldest angiosperm lineages
~ 100 species
Angiosperm diversity
• Magnoliids
• ~ 8,000 species
• Magnolias, laurels, tulip tree
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Angiosperm diversity: Monocots
Monocots
• ~70,000 species
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Angiosperm diversity: Eudicots
Eudicots ~170,000 species