gymnosperms “naked seeds”. general characteristics vascular alternation of generations...
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GYMNOSPERMSGYMNOSPERMS
““Naked Seeds”Naked Seeds”
General CharacteristicsGeneral Characteristics
Vascular Vascular
Alternation of generationsAlternation of generations– Dominant sporophyte Dominant sporophyte – Reduced, dependent gametophyteReduced, dependent gametophyte
Produce uncovered seedsProduce uncovered seeds
4 Phyla of Gymnosperms4 Phyla of Gymnosperms
CycadsCycads
GingkoGingko
ConifersConifers
GnetophytesGnetophytes
CycadsCycads
Most diverse during Most diverse during age of dinosaursage of dinosaurs
Only 100 living Only 100 living speciesspecies
Palmlike appearancePalmlike appearance Pollen-bearing and Pollen-bearing and
seed-bearing cones seed-bearing cones on different plantson different plants
Strobilus of a “female” cycad
GinkgosGinkgos
Diverse during Diverse during age of dinosaursage of dinosaurs
One surviving One surviving species, species, Ginkgo Ginkgo biloba biloba
Deciduous trees Deciduous trees are male or are male or female female
Seeds are Seeds are completely completely exposedexposed
GnetophytesGnetophytes
Share some Share some traits with traits with angiospermsangiosperms– Xylem Xylem – Cone clusters Cone clusters
resemble flower resemble flower clustersclusters
– Parts of life Parts of life cycle more like cycle more like angiospermsangiosperms
Conifers Conifers
Widest known, largest number of Widest known, largest number of living speciesliving species
Woody trees or shrubs Woody trees or shrubs Most are evergreenMost are evergreen Bear seeds on exposed cone scalesBear seeds on exposed cone scales Most produce woody conesMost produce woody cones
Pine ConesPine Cones
Woody scales of a “pine Woody scales of a “pine
cone” are the parts where cone” are the parts where
megaspores formed and megaspores formed and
developed into female developed into female
gametophytesgametophytes
Male cones, where Male cones, where
microspores and pollen microspores and pollen
are produced, are not are produced, are not
woodywoody
Life cycle of typical coniferLife cycle of typical conifer
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Animation: Pine Life CycleAnimation: Pine Life Cycle
Conifer DistributionConifer Distribution
Reproduce more slowly than Reproduce more slowly than angiosperms; at competitive angiosperms; at competitive disadvantage in many habitatsdisadvantage in many habitats
Still dominate in far north, at higher Still dominate in far north, at higher elevations, and in certain parts of elevations, and in certain parts of southern hemispheresouthern hemisphere