Bryophytes Nonvascular Plants

Nonvascular Plants are called Bryophytes

Bryophytes Bryophytes have life cycles that depend on water for reproduction. Lacking vascular tissue, these plants can draw up water by osmosis(diffusion of water) only a few centimeters above the ground. Vascular Tissue – tissue that draws up water and nutrients. Do not have true roots, stems, and leaves.

Groups of Bryophytes Bryophytes are divided into three major phyla: Mosses Liverworts Hornworts

Mosses Phylum Bryophyta Mosses grow most abundantly in areas with water (swamps, bogs, streams, rainforests) Many can tolerate low temperatures. Vary in appearance from mini evergreen trees to small, filamentous plants that form threadlike carpets.

Moss Reproduction Produce thin stalks, each containing a capsule. This is the sporophyte stage. Each moss plant has a thin, upright shoot that looks like a stem with tiny leaves. Each leaf is one cell thick. Have Rhizoids: long thin cells that anchor them in the ground and absorb water and minerals from the surrounding soil.

Moss Life Cycle

Liverworts Phylum Hepaticophyta. Have a flat, liver-shaped body called a thallus. Look almost like flat leaves attached to the ground. In their gametophyte stage they are broad and thin structures that draw up moisture directly from the surface of the soil. When they mature, the gametophytes produce structures that look like tiny green umbrellas. These structures carry the structures that produce eggs and sperm

Liverworts They can reproduce asexually using Gemmae: small multicellular spheres that contain haploid cells. These cells can divide by mitosis to produce a new individual. Gemmae

Liverwort Life Cycle

Hornworts Phylum Anthocerotophyta. Generally found only in soil that is damp nearly year round. Gametophytes look very much like those of liverworts. The sporophyte looks like a tiny green horn that grows out of the gametophyte.

Hornwort Life Cycle

Life Cycle of Bryophytes Reproduce using alternation of generation. The gametophyte is the dominant, recognizable stage of the life cycle and is the stage the carries out most of the plant’s photosynthesis. Must have water so the bryophyte can swim to the egg.

Life Cycle Cont. Spore lands in a moist place. Germinates and grows into a tangle of green filaments called a Protonema. Protonema grows and forms Rhizoids that grow into the ground and shoots that grow into the air. This is the gametophyte stage. Gametes are formed in structures at the tips of gametophytes. Antheridia produce sperm. Archegonia produce eggs. Fertilization produces a diploid zygote. This the beginning of the Sporophyte stage. Mature sporophytes produce new haploid spores through meiosis. Capsule ripens and release spores to the wind to start the cycle again.

Life Cycle Diagram

Common Uses for Mosses Sphagnum mosses are a group of mosses that thrive in acidic waters of bogs. Dried sphagnum moss absorbs many times its own weight in water and is a natural sponge. This forms peat which is used in gardening for water retention and to increase soil acidity.

Review Questions How is water essential in the life cycle of a bryophyte? List the three groups of bryophytes. In what type of habitat do they live? What is the relationship between the gametophyte and the sporophyte in mosses and other bryophytes? What is an archegonium? What is an anthridium? How are those structures important in the life cycle of a moss?