sentences:  The high concentrations of the Silurian and early Devonian, when plants were first colonising land, meant that they used water relatively efficiently.As was withdrawn from the atmosphere by plants, more water was lost in its capture, and more elegant water acquisition and transport mechanisms evolved.Plants growing upwards into the air needed a system for transporting water from the soil to all the different parts of the above-soil plant, especially to photosynthesising parts.