Chapter 30 Notes

Plant Diversity II: The Evolution of Seed plants

Concept 30.1

Seed plants are vascular plants that produce seeds

Sporophyte is the dominant generation- becomes diploid and can carry recessive alleles from one generation to the next

Concept 30.1

All seed plants are heterosporousMegasporangia: produce

megaspores that will produce female (egg-containing) gametophytes

Microsporangia: produce microspores that will produce male (sperm-containing) gametophytes

Concept 30.1

Layers of sporophyte tissue called integuments envelop the megasporangium

The developing embryo is encased in a protective seed coat and supplied with its own source of food (endosperm or cotyledons)

Concept 30.1

Concept 30.1

Seeds allow the embryo to be moved away from the parent by wind, water, and animals

Seed plants are not tied to water for fertilization; pollen grains do not need to be transported by liquid

Concept 30.1

Concept 30.2

Gymnosperms lack enclosed chambers in which seeds develop; instead, seeds develop on the surfaces of specialized leaves called sporophylls.

About 900 species of gymnosperms are divided into 4 phyla: ginkgo, cycads, gnetophytes, and conifers

Concept 30.2

Phylum Ginkgophyta:- Ginkgo biloba is the only extant species- used in herbal medicine- produce pollen and seeds on separate trees (dioecious: “two houses”)

Concept 30.2

Concept 30.2

Concept 30.2

Phylum Cycadophyta:- about 100 cycad species- palm-like appearance (but not a palm)- seeds are often passed by beetles and bees

Concept 30.2

Concept 30.2

Phylum Gnetophyta:- consists of three genera that are very different in appearance- Ephedra grows in U.S. deserts- Welwitschia grow in Africa

Concept 30.2

Concept 30.2

Phylum Coniferophyta:- conifer = “cone bearer”- called evergreens because they retain their needle-shaped leaves- male and female gametophytes appear on the same tree (monoecious: “one house”)

Concept 30.2

- conifers are among the oldest and largest organisms on Earth- we get much of our lumber and paper pulp from conifers

Concept 30.2

Concept 30.2

Concept 30.3

Phylum Anthophyta:- all angiosperms are placed in one phylum

Two classes: monocots and dicots- monocots: parallel veins in leaves- dicots: branched veins in leaves

Concept 30.3

- all are heterosporous- gametophyte is greatly reduced

reproductive parts of the flowermale parts: stamen contains the anther and filamentfemale parts: carpel contains the stigma, style, and ovary

Concept 30.3

Concept 30.3

- after fertilization, the ovule develops into a seed; the endosperm is retained in the cotyledon

- as the seed develops, the ovary begins to mature around the seed to form fruit

Concept 30.3