1. Lecture Ch. 30 ______
Chapter 30 ~ Plant Diversity II: The Evolution of Seed Plants

2. Seed Plant Reproductive Adaptations
Reduction of the gametophyte: shift from haploid to diploid condition; female gametophyte and embryo remain in sporangia (protection against drought and ionizing radiation on land?)
Advent of the seed multicellular sporophyte embryo with food supply and protective coat; heterosporous (two types of spores): megaspores--->female gametophyte--->eggs; microspores---> male gametophyte--->sperm
Evolution of pollen: develop from microspores which mature into the male gametophytes; resistant and airborne for a terrestrial environment; eliminated water (sporopollenin coats)

3. Seed Plants P. 598 Reduced gametophyte dependent on sporophyte
Gametophyte is surrounded by tissues of sporophyte
Gametophyte derives its nutrition from the sporophyte

4. Seeds - an important means of dispersing offspring
Seed consists of a sporophyte embryo packaged along with a food supply and a protective coat.
The gametophyte develops within the confines of a spore p.598 (fig. C)
Seed plants are heterosporous-means they have two different types of sporangia that produce two types of spores
Megasporangia produce megaspores which give rise to female gametophytes
Microsporangia produce microspores which give rise to male gametophytes

5. Ovule to Seed
Sporophylls are small reproductive leaves where pollen cones and ovulate cones develop
Megasporangium is surrounded by integuments
Megaspore develops inside the megasporangium
Integuments, megasporangium, megaspore make up the ovule

6. Fertilized Ovule
Female gametophyte develops inside a megaspore and produces one or more egg cells
Megaspore develops into multicellular female gametophyte
Micropyle the only opening through the integuments-allows entry of a pollen grain
Pollen grain contains a male gametophyte which develops a pollen tube that discharges

7. Gymnosperm Seed
Fertilization initiates the transformation of the ovule into a seed, which consists of a sporophyte embryo, a food supply, and a protective seed coat derived from the integuments

8. Gymnosperms Cone-bearing plants
Lack enclosed chambers (ovaries) for seeds
Ovules and seeds develop on specialized leaves called sporophylls
Ginkgo, cycads, and conifers
All are “evergreens”
Needle-shaped leaves
Vascular tissue refinement: tracheids~ water conducting and supportive element of xylem

9. Angiosperms Most diverse and geographically widespread of all plants
“Flowering plants”(Phy: Anthophyta)
Monocots: 1 embryonic seed leaf (lilies, palms, grasses, grain crops)
Dicots: 2 embryonic seed leaves (roses, peas, sunflowers, oaks, maples)
Vascular tissue refinement: vessel elements/fiber cells

10. The flower: the defining structure of angiosperms
Reproductive structure: pollen transfer; specialized shoot with modified leaves
Sepals: enclose flower before it opens
Petals: attract pollinators
Stamens: male; anther (produces pollen), filament
Carpels: female; stigma, style, ovary, ovules

11. Angiosperm life cycle Fruit (mature ovary); seeds from ovules
Pollen grains: 2 haploid cells (immature male gametophytes)
Ovules (female gametophyte~ embryo sac)
Double fertilization: 1 sperm w/ egg = diploid zygote; other sperm w/ 2 nuclei in center of sac = triploid endosperm