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Colonization and Difficulties

Several small green algae began to grow in moist soils on land. These were mostly near the water's edge. These algae took advantage of the sunlight and nutrients. They could obtain water easily.

400 Million Years Ago: some of these algae give rise to the first multicellular land plants.

Low growing plants had two difficulties of life on land: obtaining and conserving water and staying upright despite gravity and winds. The plants would figure out how to solve these problems.

Difficulties For Plants On Land
Difficulty SolutionEffect
Obtaining and Conserving WaterWaterproof coatings on aboveground plant partsReduced water loss by evaporation
Obtaining and Conserving WaterRootlike structures delved into the soil, mining water, and mineralsVascular tissues conduct water from roots to leaves.
Staying Upright Despite Gravity and WindsExtra-thick walls sorround certain cellsStems stand erect.