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Chapter 12
Seedless Plants
Key Concept Seedless plants do not produce seeds
but are well adapted for reproduction and survival.
When you think of plants, you probably think of plants,
such as trees and flowers, that make seeds. But two groups of
plants don’t make seeds. The two groups of seedless plants are
nonvascular plants and seedless vascular plants.
Nonvascular Plants
Mosses, liverworts, and hornworts do not have vascular
tissue to transport water and nutrients. Each cell of the plant
must get water from the environment or from a nearby cell. So,
nonvascular plants usually live in places that are damp. Also,
nonvascular plants are small. They grow on soil, the bark of
trees, and rocks. Mosses, liverworts, and hornworts don’t have
true stems, roots, or leaves. They do, however, have structures
that carry out the activities of stems, roots, and leaves.
Mosses
Large groups of mosses cover soil or rocks with a mat of
tiny green plants. Mosses have leafy stalks and rhizoids. A
rhizoid
rhizoid is a rootlike structure that holds nonvascular plants in
place. Rhizoids help the plants get water and nutrients. As you
can see in Figure 1, mosses have two stages in their life cycle.
During the gametophyte stage, a sperm must travel through a
thin film of water to fertilize an egg. This is sexual reproduction.
Mosses can also reproduce asexually.
What You Will Learn
• Nonvascular plants do not have
specialized vascular tissues.
• Seedless vascular plants have
specialized vascular tissues.
• Seedless plants reproduce sexually
and asexually, but they need water
to reproduce.
• Seedless plants have two stages
in their life cycle.
Why It Matters
Seedless plants play many roles in
the environment, including helping
to form soil and preventing erosion.
Vocabulary
• rhizoid
• rhizome
Graphic Organizer In your Science
Journal, create a Venn Diagram that
compares vascular plants and nonvas-
cular plants.
Gametophyte
b
d
a
The sporophyte
releases spores
into the air.
cSpores land in a
moist place, crack
open, and grow into
leafy gametophytes.
Sperm swim
through water
from the male
gametophyte
to fertilize the
egg at the top
of the female
gametophyte.
The fertilized
egg grows into
a sporophyte.
Female
Fertilized egg
Spores
Egg
Sperm
Male
Sporophyte
Gametophyte
Sporophyte
rhizoid
rhizoid (RIE ZOYD) a rootlike structure
in nonvascular plants that holds the
plants in place and helps plants get
water and nutrients
Moss Life Cycle
Figure 1
