1. Chapter 3: Plants

2. Summary
Why are plants important?
Evolution
4 major groups
Life cycle – general
Key lineages

3. Why are Plants Important?
3 categories:
 Ecosystem services
 Fuels and fibers
 Other

4. Evolution
It started with green algae, confined to a watery
environment, ~ 570 mya.
Land plants 1st appeared about 450 mya, preceding
land animals.

5. Evolution
Invasion of land presented some of the same
problems for plants as it did for animals:

6. 4 Major Groups
Based on similar characteristics and order of
evolution.
 Non-vascular land plants, mosses, liverworts and hornworts
 Vascular plants
 Seedless vascular plants, club mosses, ferns and horsetails
 Gymnosperms have “naked” seeds that protect embryo, conifers,
cycads and ginkgos.
 Angiosperms have enclosed seeds (fruits) and flowers.

8. Life Cycle
Alternates between sporophyte (2n) and
gametophyte (n) generations.
In early land plants the gametophyte stage
predominates, later the sporophyte stage dominates.

10. Nonvascular Plants (Bryophytes)
Characteristics
 Gametophytes are photosynthetic, sporophytes are attached to
gametophytes and depend on them for nutrition.
 Require water to reproduce
 Most are small and live in moist, temperate environments.

11. Non Vascular Plants
Phylum Hepaticophyta –
liverworts

12. Nonvascular plants
Phylum Anthocerophyta Phaeocerus leavis
– hornworts
 Gas Exchange: Stomata
(the rest of the plant
kingdom has stomata).
 Tiny “broom handles”
extending from rhizoids
(above ground anchors to
substrate).

13. Nonvascular Plants
Phylum Bryophyta –
mosses *source of peat
 Rhizoid = anchor,
supports “leaves” which
are 1 cell thick.

15. Vascular Plants
Major developments
 Vascular tissues to…
 Vessels – vascular tissue modified to provide structure in later
species.
 2 groups: seedless and seed bearing

16. Seedless Vascular plants
Characteristics
 Primitive vascular tissue.
 Roots
 *Still dependent on water for transport of sperm to egg.

17. Seedless Vascular Plants
Phylum Lycophyta – club
mosses
 Extinct varieties were tree-
like but surviving species
are small.
 Major source of coal.

18. Seedless Vascular Plants
Phylum Psilotophyta
 Whisk ferns: no leaves or
roots, grow on rhizoids or
they are epiphytes.
 Horsetails: photosynthetic
stems, leaves are less
prominent than stems in
some varieties. Grow well in
wet, boggy areas.

19. Seedless Vascular Plants
Phylum Pteridophyta -
ferns
 Most abundant, closest
relative to seed plants.
Fern sporangia

21. Seed-bearing Vascular Plants Ch 28
Characteristics
 Sporophyte stage dominates.
 Major development is the seed that protects embryo and allows
for a dormant period.
 2 types of gametophytes or structures:
 Male (pollen-sperm) and
 Female (ovary – eggs)

22. Seed-bearing Vascular Plants
2 groups
 Gymnosperms – “naked” seeds. Ovules (eggs) are partially
exposed on scales; sperm are motile or nonmotile.
 Angiosperms – “vessel” seeds (fruit). Ovules are totally
enclosed, sperm are motile.

23. Seed-bearing Vascular Plants
Gymnosperms – 4 phyla
 Gnetophyta –
 Cycadophyta (cycads) –
 Ginkgophyta –

24. Cycad Ginkgo

26. Seed-bearing Vascular Plants
Gymnosperms – 4 phyla cont’d
 Coniferophyta (conifers) – largest group; pines, firs, cedars,
yews, cypresses, etc.
 Produce male and female cones.
 Pollen grains and ovules develop at the base of scales. Pollen
grains float into female cones and stick on ovules.
 Female cones take 1-2 seasons to mature and release their seeds.

29. Seed-bearing Vascular Plants
Anthophyta (Angiosperms) – Characteristics
 Flowers and fruits
 Dominate the plant world

30. Seed-bearing Vascular Plants
Anthophyta – 6 clades.
 Basal angiosperms: Amborella, water lilies, star anise.
 Core angiosperms:
 Magnoliids – magnolias, laurels, etc.
 Monocots – derived from Magnoliids, 1 cotyledon (seed leaf), no
woody tissue, leaf veins parallel, flower parts are multiples of 3.
Lilies, grasses, yucca, irises
 Eudicots (true dicots) – 2 cotyledons, leaf veins are web-like,
woody tissue, flower parts are multiples of 4-5. Trees, shrubs,
annuals.

32. Figure 30-23
30-23a
Angiosperms – what is the purpose of flowers?
“Corpse” flowers smell like rotting flesh and attract carrion
flies.