Plant Evolution and Structure: Bryophytes, Vascular Plants, and Ferns

How did early bryophytes help form Earth's first soils?

By producing organic acids that weathered rock.

What did the organic matter from dead bryophytes mix with to form?

Soil.

What led to the evolution of vascular tissue in early land plants?

Competition for sunlight.

What is the primary function of vascular tissue?

To transport water and nutrients.

What is the water-transporting tissue in vascular plants?

Xylem.

What compound strengthens xylem cells and makes wood rigid?

Lignin.

What does lignin allow plants to do?

Grow taller and gain structural support.

In seedless vascular plants, what is the dominant life stage?

Sporophyte.

Why do seedless vascular plants still require water?

Because sperm must swim to the egg.

Approximately how many extant seedless vascular plant species exist today?

About 20,000.

To which group do most seedless vascular plants today belong?

Ferns.

What are the two main lineages of seedless vascular plants?

Ferns and lycophytes.

What do seedless vascular plants possess?

Lignified vascular tissue.

What specialized organs do seedless vascular plants include?

Roots, stems, and leaves.

What do branching sporophytes provide?

More locations for meiosis.

What increases with more sites for meiosis?

Genetic variation.

How are gametophytes in seedless vascular plants generally characterized?

Small and reduced.

What are lycophytes often called?

Club mosses.

What do lycophytes possess?

Vascular tissue.

What are lycophyte leaves with a single vein called?

Microphylls.

What do microphylls contain?

A single unbranched vein.

What are underground stems used for asexual reproduction called?

Rhizomes.

What are cone-like reproductive structures in lycophytes called?

Strobili.

What are leaves that bear sporangia called?

Sporophylls.

What do homosporous plants produce?

Spores of one type and size.

What is Lycopodium classified as?

Homosporous.

What do heterosporous plants produce?

Megaspores and microspores.

In Selaginella, what do microspores develop into?

Gametophytes that produce sperm.

What do megaspores develop into?

Gametophytes that produce eggs.

During which period did giant extinct lycophytes like Lepidodendron live?

Carboniferous.

What did fossilized remains of ancient lycophyte forests contribute to?

The formation of coal.

What does Polypodiopsida include?

Ferns and horsetails.

What are leaves with branching veins called?

Megaphylls.

From what are megaphylls likely evolved?

Branching stems.

What is the only living genus of horsetails?

Equisetum.

What gives horsetail stems an abrasive texture?

Silica.

What does the nickname 'scouring rush' refer to?

Its abrasive stems used for cleaning.

How are leaves in horsetails characterized?

Reduced to small scales.

Where does photosynthesis mainly occur in horsetails?

In branches and stems.

What do reproductive shoots of horsetails produce?

Strobili.

What structures do spores of horsetails possess?

Hygroscopic structures called elaters.

What are fern leaves called?

Fronds.

What are young fern leaves called when they emerge?

Fiddleheads.

What is the unfurling of fern fiddleheads called?

Circinate vernation.

What do fern sporangia form clusters called?

Sori.

What structure protects some sori?

Indusium.

What do fern sporangia use to open and release spores?

The annulus.

What is the fern gametophyte called?

Prothallus.

How are fern gametophytes typically characterized?

Heart-shaped and thalloid.

What anchors the fern gametophyte?

Rhizoids.

What is the male gametangium in ferns?

Antheridium.

What is the female gametangium in ferns?

Archegonium.

What are fern spores classified as?

Haploid.

What does fertilization in ferns produce?

A diploid zygote.

From where does the embryo sporophyte initially obtain nutrients?

From the gametophyte.

Where does meiosis in ferns occur?

In the sporangia.