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Phylum Bryophyta (Mosses)
Date:
Introduction to Land Plants: Mosses
Name:
Welcome to Phylum Bryophyta in Kindom Plantae. First, some general characteristics of Plants that you
must know:
1. Eukaryotic:
2. Multicellular:
3. Photosynthetic pigments (Cholorophyll).
4. Require: sunlight, water and gas exchange (CO2 and O2) for photosynthesis and survival.
The Evolutionary Relationships of Plants are:
Mosses represent a huge evolutionary jump for plant organisms. They are the:
Great Leap Forward! (from Green algae in the sea to Land Plants)
Colonizing Land: Think-Pair-Share2
What advantages would plants have when colonizing land?
What challenges do plants face when colonizing land from the sea?
How would you go about and solve these challenges? What adaptations would you think to see for plants
going from the bodies of water to land?
Bryophytes
What makes the bryophytes unique? What allows them to be grouped together?
1. Non- Vascular:
2. Need water for reproduction:
3. Water taken in by osmosis:
4. Leaves only one cell thick:
5. Short plants (a few centimetres) and grow low to the ground: why?
How do bryophytes solve the challenges of living and reproducing on land?
Ecological Importance
Not only do bryophytes represent the great leap forward onto land, they are natures attack front line on rocks.
Bryophytes are the second layer of plant life on rocks and create a layer of topsoil. The topsoil then allows
other plant species to grow.
Moss live in moist environments such as swamps and streams and bogs.
Here’s why:
All plants reproduce through alteration of generations (remember algae examples). We will be seeing this
over and over so here is a quick overview:
Specifically, here is the life cycle of bryophytes:
Explanation:
-A moss spore lands in a moist area and begins to grow. The new growth is called a PROTONEMA. These
protonema grow moss roots into the ground (called rhizoids) and the moss matures into a
GAMETOPHYTE. This gametophyte is the moss form we recognize (the green carpet on logs or forest
floors).
-There are male and female gametophytes at the tips of the green moss plants.
-Male: ANTHERIDIUM (where sperm (1N: Haploid) are produced)
-Female: ARCHEGONIA (where egg cells (1N: Haploid) are produced).
-Sperm and egg unite to produce a ZYGOTE (2N: Diploid) that grows and develops inside the archegonium
(singular).
-zygote grows into a stalk above the gametophyte called a SPOROPHYTE (2N: Diploid).
-Inside the capsule of the sporophyte, meiosis occurs to produce SPORES. (1N: Haploid)
-These spores are dispersed into the environment and the cycle begins again.
-Moss need water to fertilize. They have swimming sperm that requires water in order to fertilize an egg.
Water includes dew on moss blades, or raindrops splashing on the moss and spreading sperm that way.
Phylum Pterphotya: Formation of Vascular Tissue
Approx. 420 millions years ago, plants evolved to be capable of growing taller. There are specific
evolutionary adapataions that support this observation:
1. Plant Vascular Tissue:
1. Xylem: made up of Tracheid Cells. Tracheids are hollow cells with thick cell walls that move
water UPWARDS from the roots to the leaves.
2. Phloem: Transports nutrients and carbohydrates produced by photosynthesis.
Vascular tissue can work against the force of gravity.
2. Lignin: protein that makes cell walls rigid.
3. Roots, Stems, and Leaves
Diversity:
Pterophytes include:
1. Club Mosses
2. Horsetails
3. Ferns
Life Cycle of Ferns:
-
Like all plants, exhibit alternation of generations.
Need to know: Sporangium, Frond, Sporophyte, Gametopye, Embryo, Antheridium, Archegonium