Lesson 12 of 12 · 16 min
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Must-know facts
25 facts
- 1Plantae now excludes fungi and the walled members of Monera and Protista; cyanobacteria are not algae.
- 2Artificial systems (e.g. Linnaeus, androecium-based) used few, mostly vegetative characters; natural systems (Bentham and Hooker) added anatomy, embryology and phytochemistry; phylogenetic systems use evolutionary relationships.
- 3Numerical taxonomy gives every character equal weight; cytotaxonomy uses chromosomes; chemotaxonomy uses chemical constituents.
- 4Algae: chlorophyll-bearing, simple, thalloid, autotrophic, mostly aquatic.
- 5Isogamy: Ulothrix (flagellated gametes), Spirogyra (non-flagellated). Anisogamy: Eudorina. Oogamy: Volvox, Fucus.
- 6Algae do at least half of earth's CO₂ fixation.
- 7Algin: brown algae. Carrageen: red algae. Agar: Gelidium and Gracilaria. Chlorella: protein-rich food supplement.
- 8Green algae: chlorophyll a, b; starch; pyrenoids; wall of cellulose inside, pectose outside.
- 9Brown algae: chlorophyll a, c, fucoxanthin; laminarin or mannitol; algin coat; holdfast, stipe, frond; pear-shaped gametes with two unequal lateral flagella.
- 10Red algae: r-phycoerythrin; floridean starch; no flagella; oogamous; can live at great depths.
- 11Bryophytes: amphibians of the plant kingdom; haploid gametophyte is the main plant; no true roots, stems or leaves.
- 12Bryophyte sporophyte stays attached to and fed by the gametophyte.
- 13Antheridium: biflagellate antherozoids. Archegonium: flask-shaped, one egg.
- 14Sphagnum gives peat (fuel, packing material). Mosses and lichens colonise bare rock first.
- 15Marchantia: thalloid, dorsiventral liverwort; gemmae in gemma cups.
- 16Moss gametophyte: protonema (from spore) then leafy stage (lateral bud on secondary protonema).
- 17Sporophyte of bryophytes: foot, seta, capsule; mosses' is more elaborate than liverworts'.
- 18Pteridophytes: first land plants with xylem and phloem; main plant is the sporophyte with true root, stem, leaves.
- 19Microphylls in Selaginella, macrophylls in ferns; strobili in Selaginella and Equisetum.
- 20Pteridophyte gametophyte = prothallus: small, free-living, mostly photosynthetic; water needed for fertilisation.
- 21Four pteridophyte classes: Psilopsida (Psilotum), Lycopsida (Selaginella, Lycopodium), Sphenopsida (Equisetum), Pteropsida (Dryopteris, Pteris, Adiantum).
- 22Heterospory in Selaginella and Salvinia; embryo develops inside retained female gametophyte, a precursor to the seed habit.
- 23Gymnosperms: naked ovules and seeds; Pinus mycorrhiza; Cycas coralloid roots with N₂-fixing cyanobacteria.
- 24Pollen grain = reduced male gametophyte; ovule = nucellus plus envelopes; female gametophyte bears two or more archegonia.
- 25Angiosperms: pollen and ovules in flowers, seeds in fruits; Wolffia to Eucalyptus; dicots and monocots.
Common traps
Where marks are lost
Calling cyanobacteria (blue-green algae) algae.
They are prokaryotes in Monera; the chapter says they are no longer algae.
Giving Spirogyra as an example of anisogamy because its gametes do not swim.
Spirogyra's gametes are similar in size, so it is isogamous; non-flagellated does not mean unequal.
Linking algin with red algae and carrageen with brown algae.
Algin comes from brown algae, carrageen from red algae.
Saying red algae have flagellated gametes.
Rhodophyceae have no flagella; their spores and gametes are non-motile.
Giving brown algae chlorophyll a and b.
Brown algae have chlorophyll a and c with fucoxanthin; green algae have a and b; red algae have a and d.
Thinking the bryophyte sporophyte is free-living.
It stays attached to the gametophyte and depends on it for food.
Calling the leafy moss plant diploid.
The leafy stage is part of the haploid gametophyte; only the sporophyte (foot, seta, capsule) is diploid.
Saying the pteridophyte gametophyte is dependent on the sporophyte.
The prothallus is free-living and mostly photosynthetic; dependence of the female gametophyte appears only in heterosporous forms and seed plants.
Listing Equisetum under Lycopsida.
Equisetum is Sphenopsida; Selaginella and Lycopodium are Lycopsida.
Saying Pinus bears male and female cones on different trees.
Pinus bears both on the same tree; Cycas has male cones and megasporophylls on separate trees.
Swapping the root partners of Pinus and Cycas.
Pinus: mycorrhizal fungi. Cycas: coralloid roots with nitrogen-fixing cyanobacteria.
Key terms
27 terms
- Artificial system
- A classification based on a few, mostly vegetative, external characters.
- Natural system
- A classification based on natural affinities, using external and internal features.
- Phylogenetic system
- A classification based on evolutionary relationships and common ancestry.
- Numerical taxonomy
- Computer-based classification giving equal weight to every coded character.
- Cytotaxonomy
- Classification using chromosome number, structure and behaviour.
- Chemotaxonomy
- Classification using a plant's chemical constituents.
- Thallus
- A plant body not divided into true root, stem and leaves.
- Zoospore
- A flagellated, motile asexual spore.
- Isogamy
- Fusion of two gametes of similar size.
- Anisogamy
- Fusion of two gametes of unlike size.
- Oogamy
- Fusion of a large non-motile female gamete with a small motile male gamete.
- Pyrenoid
- A storage body in green algal chloroplasts holding protein and starch.
- Hydrocolloid
- A water-holding substance such as algin or carrageen.
- Holdfast
- The part that anchors a brown alga to the substratum.
- Gametophyte
- The haploid, gamete-making phase of a plant.
- Sporophyte
- The diploid phase that makes spores by meiosis.
- Antheridium
- Male sex organ; in bryophytes it makes biflagellate antherozoids.
- Archegonium
- Flask-shaped female sex organ holding a single egg.
- Gemma
- A green, multicellular asexual bud formed in a gemma cup of a liverwort.
- Protonema
- The creeping, green, filamentous first stage of a moss gametophyte.
- Sporophyll
- A leaf-like structure that bears sporangia.
- Strobilus
- A compact cone of sporophylls.
- Prothallus
- The small, free-living gametophyte of a pteridophyte.
- Heterospory
- Production of two kinds of spores, megaspores and microspores.
- Coralloid roots
- Specialised Cycas roots housing nitrogen-fixing cyanobacteria.
- Pollen grain
- The reduced male gametophyte of a seed plant.
- Ovule
- The nucellus (megasporangium) with its protective envelopes.