1. Plant Diversity

2. General Characteristics of Plants
All plants are:
Eukaryotic
Autotrophic
Multicellular
Cell Walls with cellulose
Chloroplasts w/ chlorophyll a, b, and carotenoids
May have waxy cuticle to prevent water loss.
Stomata allow gas exchange.
Plants probably evolved from green algae (charophytes)
Chloroplast similarity
Biochemical similarities
Cell Wall similarities

3. Charophytes v. Plants No alternation of generations No cuticle needed
Jacketed gametes
No protection of embryos
Alternation of generations
Cuticle (prevents water loss/dessication)
Jacketed gametes (protects from dessication)
Protected embryo
(protects from dessication)

4. Alternation of Generations
Sporophyte (2N)
Mitosis
Meiosis
Zygote (2N)
Spores (N)
fertilization
Gametes (egg & sperm
Gametophyte (N)

5. Evolutionary Trend Figure 23.2 Page 386 zygote SPOROPHYTE (2n)
GAMETOPHYTE (n)
GREEN ALGA
BRYOPHYTE
FERN
GYMNOSPERM
ANGIOSPERM

6. Classifying Plants
Plants can be divided into 2 major categories based on their characteristics:
Nonvascular Plants
Do NOT have specialized tissues to transport water and nutrients
Instead, these plants transport water from cell-to-cell by osmosis
Vascular Plants
Have specialized tissues to transport water and nutrients in plants
Xylem – carries water upward from roots
Phloem – carries nutrients and carbohydrates produced by
photosynthesis

7. Nonvascular Plants (Bryophytes)
Again, these plants do not have specialized tissues to transport water and nutrients and instead rely on osmosis
Thus, these plants must be small
Why?
Major types of bryophytes (nonvascular plants):
Mosses
Liverworts
Hornworts

8. Nonvascular Plants/ Bryophytes
Mosses
Have rhizoids that anchor them to the ground (instead of roots)
Depend on water for fertilization
The sperm must swim to the egg
Therefore, nonvascular plants must live in MOIST environments
Gametophyte is the dominant phase of the life cycle

9. Moss/ Bryophyte Life Cycle
Zygote grows, develops into a sporophyte while still attached to gametophyte.
mature sporophyte
zygote
Diploid Stage
Fertilization
Meiosis
Haploid Stage
Spores germinate.
sperm-producing structure
male gametophyte
egg-producing structure
female gametophyte
Figure 23.5 Page 388

10. Vascular Plants/Tracheophytes
Reminder:
Vascular plants have specialized tissues to transport water and nutrients in plants
Xylem & phloem
Vascular plants (tracheophytes) can be divided into 2 categories:
Seedless vascular plants
Seed (vascular) plants

11. Seedless Vascular Plants
Have true roots, leaves, and stems
Consist of ferns, club mosses, and horsetails

12. Seedless Vascular Plants
Ferns – A Close Up
Diploid sporophyte is the dominant stage
Have rhizomes, which are underground stems
Fronds: large “leaves” where spores develop
Develop spores in sporangia on underside of fronds
Reproduce using spores
A sorus (plural: sori) is a cluster of sporangia

13. Fern Life Cycle Sporophyte still attached to gametophyte sorus zygote
rhizome
Diploid Stage
fertilization
meiosis
Haploid Stage
Spores
are
released
Spores develop
egg
sperm
Figure 23.9 Page 391
mature
gametophyte
Spore germinates

14. Seed (Vascular) Plants
Have true roots, leaves, and stems
Have the ability to form seeds, which are used for reproduction
Seed plants are the most dominant group of photosynthetic organisms on land
There are 2 types of seed (vascular) plants:
1. gymnosperms
2. angiosperms

15. Seed (Vascular) Plants
Gymnosperms =
“cone bearers”
“naked seeds” – not enclosed in ovaries
Bear seeds directly on the surfaces of cones
Cones = sporophyte structures that produce
gametophytes (seeds)
Coniferous trees are the major example
Pines, junipers, spruces, etc.

16. Pine Life Cycle section through one ovule
surface view of one cone scale
(houses two ovules)
Pine Life Cycle
ovule
surface view of one cone scale
(houses a pollen-producing sac)
mature sporophyte
section through a pollen-producing sac
seed coat
zygote
seeding
embryo
Diploid
seed
fertilization
meiosis
pollen tube
Haploid
microspores form
eggs
sperm-producing cell
megaspores form
pollination
female gametophyte
Figure Page 396

17. Seed (Vascular) Plants
Angiosperms = flowering plants
Seeds are enclosed by an ovary
Flowers are reproductive organs
Evolutionary advantage  attract pollinators
Flowering plants contain ovaries
Ovaries surround and protect seeds
Ovary develops into a fruit after pollination & helps with seed dispersal when eaten
Examples:
Maple trees, tulips, grass

18. Flowering Plant Life Cycle
sporophyte
Flowering Plant Life Cycle
Diploid
Double fertilization
Meiosis
Meiosis
Haploid
mitosis without cytoplasmic division
microspores
pollination
two sperm enter ovule
Figure Page 399
female gametophyte

20. zygophytes, related groups
Evolutionary Tree for Plants
Nested monophyletic groups
flowering plants
green
algae
zygophytes, related groups
charophytes
bryophytes
lycophytes
horsetails
ferns
cycads
ginkgos
conifers
gnetophytes
seed plants
euphyllophytes
embryophytes (land plants)
vascular plants
(closely related groups)