Stanmore Country Park Nature Trail
Post 9: To the left is an isolated clump of young sycamore whose broad leaves develop large black spots in high summer. These are caused by the Tar Spot Fungus Rhytisma acerinum. The fungus was seen only rarely in London a few decades ago, because it was sensitive to air pollution. The presence of the fungus, which does no great harm to the host tree, is therefore a welcome sign of the cleaner air we now enjoy.

Look for red campion Silene dioica under the sycamore. There is a chance of seeing flowers all the way from March through October. The flowers have five petals, each deeply divided - see illustration below.

On the other side of the row of fence posts is a prominent line of male fern Dryopteris filix-mas. Follow the path to the right into the woods. Soon you pass a rather eerie area of blackthorn trunks coloured red by the filamentous alga Trentepohlia.


Image: Red Campion

To description for post 10

Click here to learn more about the Harrow Nature Conservation Forum including guided walks and conservation workdays.