Plantae Seed Plants

Vascular Plants Formation of vascular tissue –Xylem (water) –Phloem (food) –True leaves, roots, and stems Lignin ____________ generation dominate Sporophyte

Alternation of Generation

Sporophyte dependent on gametophyte –mosses Large sporophyte and small independent gametophyte –ferns Gametophyte dependent on sporophyte –seed plants

Why be Sporophyte Dominant? Reduced mutations –UV light harmful to DNA –Diploid (2n) form copes better with mutations two alleles

Why Retain Gametophyte Generation? Ability to screen alleles –doesn’t require a large amount of energy Sporophyte embryos rely on some gametophyte tissue

Seeds A seed is a sporophyte in a package –spores are only single cells –packaged with food All seed plants are _____________ (more than one kind of spore) –megasporangia –microsporangia Heterosporous

From Ovule to Seed Whole structure Develops from megaspore Embryo, food supply, protective coat

Overview of Seed Plants Produce Seeds –Can remain dormant for years –Pollination replaces swimming sperm Gametophyte generation reduced –Gymnosperms lack antheridium –Angiosperms lack both archegonium and antheridium

Phylogeny

Gymnosperms (Naked Seed) Division: Cycadophyta Division: Ginkgophyta Division: Gnetophyta Division: Coniferophyta

Ginkgophyta Ginkgo or Maidenhair Tree Characteristic leaves Only one species Only ______ are planted Males

Cycadophyta Cycads Palm-like plants –Sago Palms Leaves in cluster at top of trunks True __________ Secondary Growth

Gnetophyta 3 Genera Ephedra Mormon Tea –____________ raises heart rate raises blood pressure Ephedrine

Coniferophyta

Pine tree is the sporophyte generation Contains both male and female cones –Pollen (___________) cones (low in tree) produces pollen –Ovulate cones (high in tree) with scales produces seeds Staminate

Pine Life Cycle No Antheridium (microsporangia) produce pollen grain (4 cells) –2 prothallial cells –1 generative cell »produces 2 sperm –1 tube cell –__________ for dispersal Wings

Pine Life Cycle Ovule in a ovulate cone –integument (seed coat) (2n) –megasporangia or nucellus (nutrition) (2n) –4 _______________ from female gametophyte (3 die) develops into female gametophyte –archegonium with eggs (n) Megaspores

Angiosperms

Angiosperm

Flower Sepals Petals Receptacle (part of the stem) Stamen –Anther –Filament Carpel –Stigma –Style –Ovary with ovule

Angiosperm Life Cycle

No Antheridium (microsporangia - diploid) produce pollen grain –1 ___________ cell »produces 2 sperm –1 tube cell generative

Angiosperm Life Cycle Ovule in Ovary –megasporangia –produces 4 megaspores (3 die) remaining one develops into female gametophyte called the _____________ Embryo sac

Angiosperm Life Cycle Embryo sac (Female Gametophyte) consists of: –7 cells (eight nuclei) due to 3 mitotic divisions 3 ___________ 2 polar nuclei (one cell) 2 __________ 1 egg Antipodals Synergids

Angiosperm Life Cycle Double fertilization –one sperm unites with egg –one sperm unites with polar nuclei develops into endosperm (3n) Fruit and Seed development –ovule = seed –ovary = fruit

Angiosperm Life Cycle

Cross Pollination Most flowers do not self-pollinate –stamen and carpal may develop at different times –stamen and carpal may be arranged in flower to avoid contact

Angiosperm Radiation Begins the Cenozoic era (65 mya) Most closely related to the Gnetophyta __________ –the mutual influence of two species on each other –plants and animals (insects, birds, bats) Coevolution