Purple gromwell
Purple gromwell is a rare plant of woodland areas found on
limestone-based soils. It is limited to a small number of sites in
Wales and South West England – one of which is the cliffs at
Porthkerry country park.
Purple gromwell is a short perennial with
downy leaves. It has creeping, woody stems and spreads both
through its seeds and by its stems rooting. The flowers are funnel
shaped and at first are red, then as they open they become a deep
purpley-blue.
As the flower develops, the acidity of the cell sap changes from
acid to alkaline and the change in colour from red to blue occurs.
If you want to see this colour change happen faster and in
reverse, try putting a blue flower from a harebell or
forget-me-not on a wood ant nest. As the wood ant's spray formic
acid on the flower, small red patches will start to appear!
Like other members of the borage family, purple gromwell is
attractive to a wide range of pollinating insects.
Look for the flower in cliffwood and the
golden stairs where the rangers have been working to
improve the habitat.