Tracheophytes Flashcards
What gave vascular plants a major advantage on land
Efficient transport of water and nutrients via vascular tissue, enabling larger growth and dominance on land
How did the rise of vascular plants affect Earth’s climate
Formation of forests reduced atmospheric CO₂ and influenced global climate
What characterised early Devonian
Primitive vascular plants, transitioning from small/simple to large/complex
What organisms were (and weren’t) present at this time
No vertebrates, few arthropods
How did plant colonisation impact animal evolution
Made terrestrial environments more habitable, enabling land animal evolution
What the earliest land plant ancestor
Haplontic Zygnematalian - simple algae with only a haploid stage
What key shift occurred with the stomatophyte ancestor
Alternation of generations (haplo-diplontic lifecycle)
What are Bryophytes and what do they lack
Early land plants (e.g. mosses, liverworts) without vascular tissue
How did polysporangiate plants contribute to plant evolution
Polysporangiate plants, with multiple sporangia, improved reproductive efficiency and were a key step toward the evolution of more advanced vascular plants with complex sporophytes
What evolutionary steps led to vascular plants
Evolution of polysporangiate plants → more complex sporophytes → better reproduction & survival
What are tracheids, and what function do they serve
Tracheids are dead, lignin-thickened water-conducting cells that were the first vascular tissues in plants. They provide structural support and transport water upward in the plant
What is the role of xylem vessels in vascular plants
Found in angiosperms/gymnosperms; larger conduits for efficient water transport
How are xylem vessels different from tracheids
Xylem vessels, found in angiosperms and some gymnosperms, evolved after tracheids and are wider, more efficient conduits for water transport, allowing plants to grow taller and spread into drier areas
What distinguishes microphylls from other leaves
Small leaves with a single, unbranched vein
What are sporophylls and strobili in lycophytes
Sporophylls: Sporangia-bearing leaves
Strobili: Cones of sporophylls
Describe the Lycopodium life cycle
Sporophyte → spores → gametophyte → egg + sperm → zygote → new sporophyte
What distinguishes ferns from earlier vascular plants
Ferns were the first plants to develop megaphylls—leaves with branched veins—allowing greater surface area for photosynthesis and more efficient energy capture
What are megaphyll leaves
Leaves with branched veins → more photosynthesis
How do ferns release spires
Sporangium wall thickens unevenly → builds tension → bursts to release spores
What are sori in true ferns (Polypodiopsida)
Sori are clusters of sporangia typically found on the underside of fern leaves, where spores are produced and released
What are Marrattiopsida, Equisetopsida, and Psilotopsida
Marrattiopsida: Large tree ferns
Equisetopsida: Horsetails with jointed silica-rich stems
Psilotopsida: Primitive vascular plants like whisk ferns
What plants dominated Carboniferous forests
Lycophyte trees, tree ferns, tree horsetails, and progymnosperms
Why did lycophytes return to water for reproduction
Required moisture for sperm to reach egg despite tall sporophyte form
What was the climatic effect of carboniferous forests
Decreased CO₂ → cooling climate, coal formation due to undecomposed lignin
