Seedless Plant ReproductionChapter 7: Section 2

Seedless Plants

• How do seedless plants reproduce?• Include all nonvascular plants and some

vascular plants• Vascular vs. nonvascular• Nonvascular plants do not have structures that

transport substances through the plant– Substances move from cell to cell– Vascular plants have tube-like cells that transport

water & substances throughout the plant

Nonvascular Plants

Importance of Spores

• If you want to grow plants (mosses or ferns) that reproduce by spores, can you buy a packet of seeds?

• These plants do not reproduce by seeds• Mosses and ferns contain parts called spore

cases• Spore cases contain spores; when they break

open spores are released – how are they spread?

Nonvascular Seedless Plants

• Mosses are an example of nonvascular plants

• Sporophyte stage of these plants is small and is easily overlooked

• Mosses are green, low-growing masses of plants

• This is the gametophyte stage (which produces sex cells)

Nonvascular Seedless Plants

• If you were to look closely at the moss, you might see brown stalks growing up from the tip of the plant

• This is the Sporophyte stage• Brown capsules are on tips of plants• Contain millions of spores• When conditions are right, capsule opens and spores

fall to ground or are carried by wind• New mosses can grow from each spore & cycle

begins again– Figure 6: page 209

Nonvascular Plants

• Nonvascular plants can also reproduce asexually

• If a piece of moss gametophyte breaks off, it can grow into a new plant

• Liverworts: form small balls of cells on surface of gametophyte plant; then carried away by water and grow into a new gametophyte plant if they settle in the right environment

Vascular Seedless Plants

• Millions of years ago most plants were vascular seedless plants

• Most are ferns but others include horsetails and club mosses

• All of these plants have structures to transport water and nutrients in the plant

• The gametophyte stage is small and often over-looked

Ferns

• Fern plants seen in nature and houses are fern sporophyte plants

• Fern leaves are called fronds• Fronds grow from underground

stem called rhizomes• Roots that anchor plant also

grow from rhizomes• Fern sporophytes make food by

photosynthesis

Ferns• Fern spores produced in structures

called sori (sorus) usually on underside of fronds

• Sori look like crusty, rust-brown bumps

• If a fern spore lands on damp soil it can grow into a small, green, heart-shaped gametophyte called a prothallus– Very hard to see because they are very

small (5mm-6mm)– Prothallus contains chlorophyll

Ferns • Ferns can reproduce asexually,

also• Fern rhizomes grow and form

branches• New fronds and roots develop

from each branch• The new rhizome branch can be

separated from the main plant• It can then grow on its own and

form more fern plants

Section 2: Summary

• Seedless plants reproduce by forming _______. • Seedless plants include all nonvascular plants

and some vascular plants. • Spores are produced by the sporophyte stage

and can grow into gametophyte plants• The sporophyte ________ photosynthesize.• Fern sporophytes have green fronds that grow

from underground rhizomes.

Review Questions

1. Describe the life cycle of mosses.2. Explain the stages of the life cycle of a fern.3. Compare and contrast the gametophyte plant

of a moss and the gametophyte plant of a fern.4. Describe asexual reproduction in seedless

plants.5. Why do some seedless plants reproduce only

asexually during dry times of the year?