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 heterosporous
Megasporangia: produce megaspores
that will produce female (eggcontaining) gametophytes
Microsporangia: produce microspores
that will produce male (spermcontaining) 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 flower
male parts: stamen contains the
anther and filament
female 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