Pine cone science

An interesting natural mechanism: how pine cones open and close

Safe­ty pre­cau­tions

Warn­ing: only un­der adult su­per­vi­sion.

Equip­ment:

  • glass;
  • glue;
  • pine cone;
  • boil­ing wa­ter.

Step-by-step in­struc­tions

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!

Process de­scrip­tion

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!