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

CLICKTO PLAY

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