13 | Botany: How do tall trees drink?

The glass tube that proved Dixon's theory

Entrance to School of Botany

It can be over 100 metres from the soil to the top of the tallest trees. So how does the water in the soil rise to that height? TCD botanist Prof Henry Dixon (1879-1953), working with his colleague, the geophysicist Prof John Joly, explained how – and it all comes down to physics, and the cohesiveness of water.

If you're taking this trail during business hours, then you can visit the Botany Department ¹ to see a small display that explains the Dixon-Joly theory.

Another noted Trinity botanist was Prof William Henry Harvey (1811-66) who first realised that we can classify seaweeds on the seashore by their colour, from grass green seaweeds on the upper shore, to the red underwater weeds of the lowest shore.

Botany reseach at TCD today includes conservation of endangered species in Ireland and around the world, the special ecology of the seasonal turlough lakes that are unique to Ireland’s limestone region, and the impact of climate change.

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• Track 13 | How tall trees drink (6 mins) [MP3, 5.10mB]

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