1. The Bryophytes Mosses, Liverworts, & Hornworts
Chapter 22

2. Evolution of Land Plants
Land plants evolved from green algae
Evidences:
Share chemical & metabolic traits
Same photosynthetic pigments
Store excess carbohydrates as starch
Cellulose is a major component of both cell walls
The most direct ancestors of plants are the Charophytes “stoneworts”

3. Adaptations for Life on Land
Cuticle
Waxy covering over the epidermis of aerial plant parts
Prevents desiccation “water loss”
Stomata
Small pore in the plant epidermis
Allows gas exchange for photosynthesis

4. Alternation of Generations
The Plant Life Cycle
Alternation of Generations
Haploid (gametophyte) stage alternates with a diploid (sporophyte) stage in the life cycle

5. Plant Reproduction Gametangia – Plant sex organs
Consists of 2 parts:
A protective outer layer of sterile (non-reproductive) cells
Gametes – sperm or egg cells.
Male Gametangia = Antheridium
Bears numerous sperm cells
Female Gametangia = Archegonium
Bears a single egg cell

6. Moss Gametangia
Antheridium – Male
Archegonium – Female

7. 4 Main Groups of Plants Bryophytes – Nonvascular; spores
Mosses
Stoneworts
Liverworts
Seedless vascular plants; spores
Club Mosses
Ferns, whisk ferns, and horsetails
Gymnosperms; seeds
Conifers
Cycads
Ginkgoes
Gnetophytes
Angiosperms “Flowering plants”; seeds
Monocots
Eudicots

8. Quiz! What is vascular tissue?
What are the two types of tissue that make up the vascular tissue system?
What does each tissue do?

9. Bryophytes “moss plant” Nonvascular plants Some have a cuticle
Cannot extensively transport water, sugar, and minerals
Rely on diffusion and osmosis to obtain water and dissolved nutrients
Typically small
Some have a cuticle
Some absorb water directly through leaf surfaces
Most require moist environments to reproduce

10. Bryphytes 3 Phyla of Bryophytes All are Gametophyte dominant
Phylum Bryophyta: Mosses
Phylum Hepatophyta: Liverworts
Phylum Anthocerophyta: Hornworts
All are Gametophyte dominant
Spend most of their life cycle in the gametophyte stage
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11. Mosses Location: soil, rocks, tree bark Help form soil
Colonize rocky sites that were previously colonized by lichens
Prevent soil erosion
Grow packed together in dense colonies
The Moss Body
Thallus – Body structure
Rhizoids – hair-like absorptive structures
Do not have true roots, stems, or leaves
Many mosses have separate sexes: male plants and female plants
The gametophyte generation is dominant

12. Lifecycle of Mosses: Read p. 435
A filament of haploid cells that grows from a spore
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13. Bryophytes
Gametophyte Generation
Sporophyte Generation

14. Liverworts Thallus Gemmae A body that lacks roots, stems, or leaves
Liverworts get their name from their liver shaped thallus
Gemmae
Asexual reproductive structure of liverworts
Small balls of tissue
Borne in a saucer-shaped structure – gemmae cup
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15. Hornworts Location: fields & roadsides Thalloids - 1-2 cm
Sporophyte generations form hornlike projections out of the gametophyte thallus

16. Hornworts