St John’s Wort

Very different weather to the sweltering temperatures last Sunday. 
This year when I see a wild flower if I am not sure what it is I am checking it using an app called Picturethis. When I was growing up, in a country village in Somerset, I regularly picked wild flowers and brought them home to identify them. However now I live in outer London there are some other plants  I am not so familiar with so need to check. There is lots of this growing on the Thames towpath.
This type is Tutsan ( hypericum androsaemum) also known as Goatweed.

It is called St John’s  Wort from the fact that in England it was traditionally harvested on St John’s Day (24th June) and then left outside people’s homes as protection from bad omens or illnesses.
I have also discovered that St John’s Wort is also sometimes used for medicinal purposes and you can buy it nowadays as a herbal supplement which among other things apparently can be used to treat mild depression and help with getting to sleep !

All new to me.