BIOL1030 Chap.2 Plants and Fungi Colonise the Land
Plants and Fungi Colonise the Land
Plants and Fungi Colonise the Land follows the Week 2 lectures from charophyte algae to seed plants and then to the fungi. It sets out the characters plants share with charophytes, such as rings of cellulose-synthesising proteins and the phragmoplast, and uses an aeroterrestrial alga and a desmid life cycle as starting points.
Alternation of generations is then traced across bryophytes, seedless vascular plants and seed plants, as the dominant generation shifts from gametophyte to sporophyte. The fungal half covers mycelia and coenocytic hyphae, budding and spores, the nucleariid relatives and the posterior flagellum, the main fungal groups, endo- and ectomycorrhizae, lichens, and the snowflake yeast experiments on how multicellularity evolves.
What this chapter covers
- 01
Characters shared by charophytes and land plants
- 02
Alternation of generations and which generation dominates
- 03
Bryophytes, seedless vascular plants and seed plants
- 04
Mycelium, hyphae, budding and asexual spores
- 05
Chytrids, zygomycetes, glomeromycetes, ascomycetes and basidiomycetes
- 06
Lichens and mycorrhizae as partnerships
- 07
Snowflake yeast and the evolution of multicellularity
Worked example · free
Rank which generation dominates in three plant groups
- 1Moss: the gametophyte is the dominant green plant, and the sporophyte stays attached to it and depends on it.
- 1Fern: the sporophyte is dominant and independent, while the small gametophyte is still free-living.
- 1Flowering plant: the sporophyte is dominant, and the microscopic gametophyte develops inside its tissues and depends on it.
Key terms
- Gametophyte
- The haploid multicellular generation of a plant that produces gametes.
- Sporophyte
- The diploid multicellular generation of a plant that produces spores by meiosis.
- Phragmoplast
- A group of microtubules that forms between daughter nuclei and guides the new cell plate.
- Mycelium
- The network of hyphae that makes up the body of most fungi.
- Lichen
- A partnership between a fungus and photosynthetic algae or cyanobacteria that forms one body.
- Arbuscular mycorrhiza
- A root partnership in which fungal arbuscules form inside the plant's cells.
Plants and Fungi Colonise the Land FAQ
What is alternation of generations in plants?
It is a life cycle with two multicellular stages. The haploid gametophyte produces gametes, fertilisation makes a diploid sporophyte, and the sporophyte produces spores by meiosis that grow into new gametophytes. Land plants differ in which stage is larger and longer-lived, which is why the moss you see and the fern you see belong to different generations.
Why are chytrids called paraphyletic?
The chytrid label gathers early fungal lineages that still have flagella, but it leaves out descendants of the same ancestors that lost the flagellum. Because the group does not contain all descendants of its common ancestor, it does not form a clade, even though the name is useful in everyday description.
What makes a lichen more than a fungus?
A lichen is a joint body. Algae, and in some species cyanobacteria, live in layers inside a fungal scaffold: the photosynthetic partners provide sugars and sometimes nitrogen, while the fungus provides structure and shelter. Many of the fungi involved are ascomycetes, a third to a half of whose species form lichens.
Why are lichens included with the fungi?
Lichens are partnerships in which a fungus builds a layered scaffold that hosts green algae, and sometimes cyanobacteria as well, under its upper surface. The fungal partner is usually an ascomycete, and between a third and a half of ascomycete species form lichens, so they are a major part of fungal diversity rather than a side topic.
Exam move
Build two comparison sheets. On the plant sheet, draw a three-row table for bryophytes, seedless vascular plants and seed plants, and fill in the dominant generation, whether the gametophyte is free-living and one example from the lecture, then sketch the desmid life cycle beside it to show how little time the alga spends diploid.
On the fungal sheet, list the five groups with one defining feature and one example each, and add the two mycorrhiza types and the lichen partners. Test yourself by explaining the snowflake yeast result in two sentences, and check each answer against the recommended readings on fungi and lichens if a term feels uncertain.
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