Class Notes  

Members of the plant kingdom are green (they all contain chlorophyll) and most are rooted in soil. There are more than 250,000 species within the kingdom.

Check out these predator plants!
 

Plant classification:

Land plants are divided into two groups (vascular and nonvascular) based on whether they have vascular tissues or not. Vascular tissues are specialized for conducting food and water within the plant. All nonvascular plants are placed in one division. There are nine divisions of vascular plants based on whether they form seeds or not. This class will be concerned with the following groups:

Division Bryophyta - nonvascular plants

• Class Musci - the mosses
Division Pterophyta - ferns, a group of seedless plants

Division Coniferophyta - cone-forming seed plants

Division Anthophyta - fruit-forming seed plants

• Class Monocotyledonae - plants with one seed leaf
• Class Dicotyledonae - plants with two seed leaves

Nonvascular plants do not have vascular tissues, roots, stems, or leaves.
Nonvascular plants are much smaller than most vascular plants.
Vascular plants live in more types of environments than nonvascular plants.

There are more than 10,000 species of moss plants. Mosses don't receive as much attention as flowering plants, ferns, or conifers because most are small and inconspicuous. They have no vascular tissue or wood, nor do they have large leaves or showy cones or flowers. This does not mean that mosses are not important. Mosses play important roles in reducing erosion along streams, water and nutrient cycling in tropical forests, and insulating the arctic permafrost.

• Mosses have structures that anchor them and absorb water as well as structures that catch sunlight for photosynthesis, but they have no true roots or leaves.
• The sphagnum moss is known for its moisture holding capacity, absorbing up to 20 times its dry weight with water.

Mosses reproduce sexually by forming spores.
A single moss "plant" is a gametophyte. Sperm from one gametophyte fertilizes the egg of another, producting a zygote.	A stalk-like structure, called a Sporophyte, with a capsule at the top containing the spores grows from the zygote.
When released, the spores will grow into new gametophytes. All mosses show alteration of generations. View the moss lifecycle.

Ferns:

Ferns are vascular plants forming true roots, stems, and leaves. They reproduce sexually by forming spores, not seeds. There was a time when ferns were the dominant form of plant life on Earth. Today, their distribution is limited by the requirement of having drops of water at a certain time for reproduction.

Ferns range in size from just a few inches to 25 meters in height. Ferns can be recognized by the "feathery" appearance of their leaves. The leaves of a fern are known as fronds. Spores form in sacs called sporangia on the under side of the fronds. Many ferns form a horizontal stem (rhizome) instead of a vertical one.

View the fern lifecycle.

The seed-forming plants:

A seed is a fertilized ovule (part of the plant ovary). It is a multicellular structure containing an embryo plant and its food. Seeds can survive long periods of inactivity between their formation and activation. Today, seed plants are the most successful plants on Earth.

Seed plants are broken into two groups based on how their seeds are formed:

Gymnosperms: plants that produce "naked" seeds.
	Gymnosperm seeds are protected by a "cone". Pollen cones (male) produce pollen. Seed cones (female) produce the seed. There are about 700 species of gymnosperms.
Angiosperms: plants that produce seeds enclosed in a fruit.
Is this a Monocot or Dicot?	Class Monocotyledoneae:  Monocots have one cotyledon, or "seed leaf". About 90,000 species are known. Class Dicotyledoneae:  The embryo plant of a dicot has two seed leaves. About 185,000 species are known. View the flowering plant lifecycle.

Monocots and dicots are easily distinguished by their physical characteristics.

Home Page

Assignments