Plant Diversity

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Slide 12

Groups of Bryophytes

Bryophytes have life cycles that depend on water for reproduction.

Bryophytes draw up water by osmosis only a few centimeters above the ground.

Slide 13

Groups of Bryophytes

The three groups of bryophytes are:

mosses

liverworts

hornworts

Slide 14

Groups of Bryophytes

Mosses

The most common bryophytes are mosses.

Mosses:

are adapted to life in wet habitats and nutrient-poor soils.

can tolerate low temperatures.

are clumps of gametophytes growing together.

Slide 15

Structure of a Moss Plant

Stalk

Capsule

Sporophyte

Gametophyte

Stem like structure

Leaf like structure

Rhizoid

Slide 16

Human Use of Mosses

Sphagnum mosses thrive in the acidic water of bogs.

Dried sphagnum acts as a natural sponge. It can accumulate to form peat deposits.

Peat can be cut from the ground and used as fuel.

Peat can be used to improve the soil’s ability to retain water and to increase soil acidity.

Slide 17

Seedless Vascular Plants

Slide 18

Evolution of Vascular Tissue

420 million years ago, moss-like plants on land were joined by taller plants.

Evidence shows that these plants had vascular tissue, which is specialized to conduct water and nutrients throughout the plant.

Slide 19

Vascular Evolution

Slide 20

Evolution of Vascular Tissue

The first vascular plants contained tracheids which are cells specialized to conduct water.

Tracheids make up XYLEM, a transport subsystem that carries water from the roots to every part of a plant.

Slide 21

More Vascular Tissue

Second transport subsystem composed of vascular tissue called PHLOEM.

Phloem transports solutions of nutrients and carbohydrates produced by photosynthesis.

Xylem (H2O)

Phloem

Slide 22

Evolution of Vascular Tissue

How is vascular tissue important to ferns and their relatives?

Both xylem and phloem can move fluids through the plant body, even against the force of gravity.