Lesson 12 of 12 · 16 min
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Must-know facts
25 facts
- 01Plantae now excludes fungi and the walled members of Monera and Protista; cyanobacteria are not algae.
- 02Artificial 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.
- 03Numerical taxonomy gives every character equal weight; cytotaxonomy uses chromosomes; chemotaxonomy uses chemical constituents.
- 04Algae: chlorophyll-bearing, simple, thalloid, autotrophic, mostly aquatic.
- 05Isogamy: Ulothrix (flagellated gametes), Spirogyra (non-flagellated). Anisogamy: Eudorina. Oogamy: Volvox, Fucus.
- 06Algae do at least half of earth's CO₂ fixation.
- 07Algin: brown algae. Carrageen: red algae. Agar: Gelidium and Gracilaria. Chlorella: protein-rich food supplement.
- 08Green algae: chlorophyll a, b; starch; pyrenoids; wall of cellulose inside, pectose outside.
- 09Brown 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.
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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.