Madder and madder

An unusual-looking weed I have been nursing along in a seed tray wher it sowed itself has now flowered and turns out to be field madder (Sherardia arvensis).  Although common in Britain and across the temperate world, this is the first time I have come across it.

Like its related species common madder (Rubia tinctorum) and wild madder (Rubia peregrina), field madder has been used to make a red or pink dye.  The generic name Sherardia is in honour of the 17th/18th century English botanist William Sherard.

In the welcome spring sunshine witches' brooms show up well among the pale green leaves and the blue sky.  They are probably caused by the fungus Taphrina betulina, but sometimes by other organisms.