Seedless Plant Reproduction Chapter 7 Section 2 Seedless

Seedless Plant Reproduction Chapter 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, lowgrowing 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, heartshaped gametophyte called a prothallus – Very hard to see because they are very small (5 mm-6 mm) – 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?