Virtual Museum of Canada
Jardin botanique de Montréal 
Centre for Forest Research

Protecting its own future

In order to grow in length, each root has stem cells at its tip that divide and produce new cells almost endlessly. These undifferentiated cells, found in the meristematic (Tissue composed of cells able to divide into new specialized tissues.) tissue, are protected by the root cap (Thimble-shaped mass of cells covering and protecting the growing tip of a root. ). This cap plays a vital role, protecting the meristem from abrasion by the rough soil, which would otherwise scrape off the precious cells.

A researcher who (very patiently!) dissected a cubic centimetre of soil under a red oak found about one thousand root tips in it. The tiny roots took up only about 3% of the volume of the soil sample. The researcher extrapolated these results to suggest that a mature oak could have five hundred million live root caps. That's the current population of Europe.

Schematic of a root cap
Root cap
© National Research Council Of Canada, NRC Research Press