1 Review In what kind of environments are green algae found

2 Apply Concepts How is water essential to the life cycle of a bryophyte

3 Review What function do vascular tissues allow Infer The size of plants increase dramatically with

the evolution of vascular tissue. How might these two events be related

CH 22 INTRODUCTION TO PLANTS22.2 Seedless Plants

Green Algae

“Green algae” are classified with plants “Algae” applies to any photosynthetic eukaryote

other than a land plant Found in fresh and salt water Absorb moisture and nutrients directly from their

surroundings.

Switch back and forth between haploid and diploid Not always with every generation.

Life Cycle of Chlamydomonas

Haploid and asexual under suitable conditions.

Life Cycle of Chlamydomonas

Unfavorable conditions uses sexual reproduction Release gametes that fuse into a diploid zygote

(sporophyte) with thick protective wall.

Zygote begins to grow once conditions become favorable

Divides by meiosis to produce four haploid cells that swim away, mature, and reproduce asexually.

Bryophytes

Mosses, hornworts, and liverworts Specialized reproductive organs enclosed by other,

non-reproductive cells.

Mosses and Other Bryophytes

Waxy, protective coating that makes it possible for them to resist drying

Rhizoids Thin filaments that anchor them

to the soil Absorb water and minerals.

Why Bryophytes Are Small

Do not make lignin, a substance that hardens cell walls

Do not contain true vascular tissue.

Alternation of Generations

Gametophyte Dominant,

recognizable stage Carries out most of

the photosynthesis.

Sporophyte Dependent on gametophyte

for water and nutrients.

Sperm swim to egg using flagella Needs water for fertilization.

Gametophyte

Spore sprouts and grows into gametophyte Forms rhizoids that grow into ground and shoots

that grow into the air.

Gametes are formed in reproductive structures at the tips of the gametophytes

Archegonia- where eggs are produced Antheridia- where sperm are produced

Egg and sperm fuse to form zygote Zygote marks the beginning of the sporophyte

stage.

Sporophyte grows within the gametophyte, depending on it for water and nutrients.

Sporophyte grows out of the gametophyte and develops a long stalk ending in a capsule called the sporangium.

Haploid spores produced in capsule by meiosis Released when capsule ripens and opens.

Vascular Plants

Contain vascular tissue (xylem and phloem) Enables vascular plants to move fluids through

their bodies against the force of gravity.

Xylem Carries water and minerals up from the roots

Phloem Carries sugar and carbohydrates from photosynthesis.

Seedless Vascular Plants

Club mosses, horsetails, and ferns True vascular tissues Strong roots Rhizomes Large leaves called fronds.

Spores produced by the sporophyte grow into thin, heart-shaped haploid gametophytes.

Sperm and eggs are produced in antheridia (sperm) and archegonia (egg)

Fertilization requires water.

Diploid zygote develops into a new sporophyte plant

Dominant stage Haploid spores develop on

the undersides of the fronds in sporangia.

Keeping Ferns in Check

Ferns often crowd out tree seedlings blocking efforts to regrow trees after logging.

To understand the fern better, scientists measured the number of viable spores per square centimeter of soil at various distances from existing ferns.

They counted spores in July as the ferns were just starting to grow and in November after spores had been released.

Graph the data from the table. Be sure to plot the data from July on one line and November on a second. Be sure the graph is fully labeled and oriented correctly.

1. Calculate What percentage of the spores after dispersal are found within 4 meters of the parent plants

2. Interpret Graphs Are spore numbers higher before or after dispersal- Explain

3. Draw Conclusions Would cutting down nearby clusters of ferns prevent ferns from invading patches of the forest that have just been cut for timber- explain your reasoning based on the data