Unit 9: Plants                                                               1   2   3   4   5   6

2. Classification of plants

2.1. Non-seed plants

This group includes mosses and ferns. They do not form flowers or seeds. They have a complex life cycle with alternation of generations. That is there are a sexual stage (gametophyte, which produce gametes) and an asexual stage (sporophyte, which produce spores).

They only grow in damp, shady places, because they depend on the water to reproduce.

a) Bryophytes (mosses)

They are the most primitive plants on the Earth.

They are very small plants that only grow at ground level.

They do not have conductive vessels. They are non-vascular plants.

Mosses have false organs. These structures are similar to true leaves, stems and roots, but they do not make the same functions.

They obtain water and nutrients through their whole surface.

Mosses reproduce by spores which are formed in a sporangium called capsule.

b) Pteridophytes (ferns)

They are bigger than mosses, but they are usually shorter than 1.5 metres tall.

They have conductive vessels. They are vascular plants.

Ferns have true organs: rhizome (underground stem) with roots and fronds (leaves)

The spores are produced in sporangia called sori which are usually on the underside of fronds.

2.1. Relate the letters with the names on the column.

        Indicate what represent every picture:

a. Why are moss leaves, roots and stems called “false”?

b. Why do Pteridophytes need a vascular system and Bryophytes don’t?

c. Where do ferns produce spores? Where do mosses do it?

d. What does it mean that Pteridophytes and Bryophytes have

    “alternation of generations”?