topic 4: terrestrialization (org. bio)

Lichen

composite organism resulting from a symbiotic relationship between a fungus and an algae or cyanobacteria. They are pioneers, often growing on bare rock

Pioneer species

Make soil by both physical and chemical weathering

Photobiont / Mycobiont

• The two parts of a lichen

• photobiont is the photosynthetic partner (algae/cyanobacteria) that provides food

• mycobiont is the fungal partner that provides structure and protection.

Soredia

mall clusters of algal cells wrapped in fungal hyphae used for asexual reproduction. They break off and are carried by wind to start a new lichen

“Seed-free” plants

A broad category of plants that reproduce via spores rather than seeds. This includes bryophytes, lycophytes, and monilophyte (ferns)

Bryophyte

Non-vascular land plants, including liverworts, mosses, and hornworts, whose life cycles are dominated by the gametophyte generation

Desiccation

The state of extreme dryness or the process of drying out

Early land plants had to evolve traits to prevent this

Phyllids

Leaf-like structures found on bryophytes

Unlike true leaves, they lack complex vascular tissue (veins)

Rhizoids

Thin, root-like filaments that anchor bryophytes and some fungi to the ground but do not play a primary role in water absorption

Gametangia

Multicellular organs where gametes are produced

Archegonia

Gametangia that produce and protect the egg

Antheridia

Gametangia that produce and release sperm

Embryo

A young sporophyte that is retained within the tissues of the female gametophyte for protection and nourishment

Cuticle

A waxy, water-repellent covering on the surface of stems and leaves that prevents desiccation

Sporangia

Multicellular organs where meiosis occurs and spores are produced

Sporopollenin

A durable, chemically inert polymer that coats spores and pollen, protecting them from dehydration and UV damage

Peat

Partly decayed organic material often found in huge, acidic, and anoxic wetlands called peatlands

Example: Sphagnum peat, used as fuel or garden soil condition

Lycophyte

A group of seedless vascular plants that includes club mosses, spikemosses, and quillworts

Monilophyte

A group of seedless vascular plants that includes ferns, horsetails, and whisk ferns

Microphyll

Small leaf with a single vein (found in Lycophytes)

Megaphyll

Large leaf with a branched vascular system (found in Ferns)

Sporophyll

Specialized leaves that form sporangia

Sorus

A cluster of sporangia on the underside of a fern frond

Example: The orange or brown dots on the back of a Boston Fern leaf

Carboniferous Period

A historical period characterized by a dramatic drawdown of atmospheric carbon dioxide by plants, leading to Earth's cooling and the formation of modern geological carbon stores

Azolla

genus of floating water fern

The Azolla Event

The "Azolla Event" refers to a massive bloom of these ferns in the Arctic Ocean ~49 million years ago that pulled so much $CO_2$ from the atmosphere it cooled the entire planet

What is the role of sporopollenin in land plants?

It is a durable polymer that makes spores resistant to harsh environments, allowing them to be dispersed through the air without drying out

Which generation is dominant in the bryophyte life cycle

The gametophyte (1n) generation is dominant; the sporophyte is attached to and dependent on it

What is a major limitation of bryophyte anatomy?

They lack a vascular system and cannot transport water long distances, which generally keeps them small and restricted to moist environments

What structural innovation allows vascular plants to grow tall?

Lignification of the stem vascular tissue increases functional strength, providing the support needed for vertical growth

Why are peatlands considered a "massive carbon sink"?

hough they cover only 3% of Earth's surface, they store 25% of all soil carbon—double the amount stored in all global forests combined

Why is the warming and drying of peatlands a climate risk?

It makes them susceptible to fires, which can release centuries of stored carbon "in a relative instant," turning a long-term sink into a major carbon source