The Bryophytes Mosses, Liverworts, & Hornworts Chapter 22

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”

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

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

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

Moss Gametangia Antheridium – Male Archegonium – Female

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

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

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

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 6th Hour Left off Here

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

Lifecycle of Mosses: Read p. 435 A filament of haploid cells that grows from a spore 2nd Hour Left off Here

Bryophytes Gametophyte Generation Sporophyte Generation

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 1st Hour Left off Here

Hornworts Location: fields & roadsides Thalloids - 1-2 cm Sporophyte generations form hornlike projections out of the gametophyte thallus

Hornworts