Conifers BIOL 1407

Seed Plants Vascular Tissue Produce seeds –Dispersal of offspring Produce pollen Sperm transfer without water

Seed Plants Sporophyte dominant Gametophytes –Greatly reduced in size –Dependent on sporophyte

Seed Plants Heterosporous –Megaspore Grows into female gametophyte  eggs –Microspore Grows into male gametophyte  sperm –Photo Credit for Ovulate Cone: Dr. Stephen Bostic, ACC –Circled area: Ovule

Pollen Production Pollen cones have microsporophylls Each microsporophyll has microsporangia Photo Credit for Immature Male Pine Cones: Menchi, Wikimedia Commons

Pollen Production Meiosis occurs within microsporangia  microspores Photo Credit for Staminate Cone: Dr. Stephen Bostic, ACC Microsporangium circled in red Microsporophyll at tip of yellow pointer Microspores circled in pink

Pollen Production Microspores grow into male gametophytes Male gametophyte = pollen grain

Pollination Pollen is released Travels from male to female Pollination occurs when pollen grain lands on female watch?v=Bwl4g48-uIEhttp:// watch?v=Bwl4g48-uIE

Pollen Germination After landing  pollen coat breaks open 1 cell produces pollen tube Photo Credit: Dr. David Byres, Florida Community College at Jacksonville

Pollen Germination A different cell produces 2 sperm cells by mitosis They will move down pollen tube as it grows Photo Credit: Dr. David Byres, Florida Community College at Jacksonville

Pollen Germination Pollen tube digests its way through female tissues to reach the egg

Ovules Ovulate cones have megasporophylls Each megasporophyll has ovules containing megasporangia Photo Credit for Immature Female Ponderosa Pine Cones: Susan USDA-NRCS PLANTS Database

Ovules Meiosis occurs within megasporangium  forms 1 megaspore and 3 haploid nuclei (degenerate) Photo Credit: Dr. Stephen Bostic, ACC Megasporangium circled in red Megasporophyll at tip of yellow pointer

Ovules Megaspore grows into female gametophyte Female gametophyte makes 1-2 eggs by mitosis

Ovules Integuments surround female gametophyte Micropyle  lets pollen reach female gametophyte

Ovules  Seeds Integuments  seed coat Female gametophyte  food supply Fertilized egg  embryo

Seeds Dispersed by: –Wind –Animals –Water –Mechanical Photo Credit for Pitch Pine Seeds: Steve USDA-NRCS PLANTS Database

Types of Seed Plants Gymnosperms –Naked Seeds –Not enclosed in ovaries –No fruits or flowers

Types of Seed Plants Angiosperms –Flowering Plants –Seeds enclosed in ovaries –Fruits and flowers

Modern Gymnosperms Conifers –Oldest living plants –Largest living plants –Widespread –Reproductive structure: Cones

Modern Gymnosperms Cycads –Wiry leaves –“Sago palms” Ginkgos Deciduous trees One species Herbal supplement

Modern Gymnosperms Gnetophytes –Ephedra (Mormon tea) –Welwitschia

The End Unless otherwise specified, all images in this presentation came from: Campbell, et al Biology, 8 th ed. Pearson Benjamin Cummings.