Pine cone science

An interesting natural mechanism: how pine cones open and close

Equipment: glass, glue, pine cone, boiling water.

Glue a pine cone to the bottom of a glass and fill the glass with boiling water – in about half an hour, the cone’s scales will press noticeably towards its center, and the cone will close! But not permanently: if you leave it to dry, it will reopen in about two days!

Most of the water that the cone absorbs ends up in the scales. Each scale has two layers – an inner layer and an outer layer. As they absorb water, the scales’ layers expand, the outer layer more dramatically than the inner one. The change in the scales’ specific shape presses them towards the center of the cone. Thus, the cone closes as it absorbs water. If you leave it in the open air, the process will reverse – the scales will start to dry out and shrink, the outer layer again more so than the inner one, forcing the scales to unfurl and allowing the cone to reopen. Similar processes allow pine cones to protect their seeds from excess moisture in their natural environment.
Safe and fun experiments for the whole family are waiting for you in the MEL Kids subscription!

Warning! Only under adult supervision