Monday, 9 June 2014

Finding the xylem in rhubarb

Today we carried out an experiment in the garden to show the location of xylem in a rhubarb stem. Xylem is the tissue in the stem that conducts water on its journey from the root to the leaves.

First we mixed some Dr Oetker blue gel food colouring with some warm water. The we picked a rhubarb leaf in the garden, cut the very end off, and submerged the cut surface of the leaf stem in the blue dye. We left it in position for an hour. 
After an hour we cut through the stem a couple of inches from the bottom. Looking at it by eye, there were many blue dots visible, which correspond to the xylem tissue that has been conducting the water containing blue dye. 
The piece of stem that had been cut off was allowed to dry for an hour. Once the tissue was dry the blue xylem tissue was much more clearly visible.

This is a close-up of a lengthwise section showing a clear xylem vessel running the full length of the section.