I mentioned seeing Purple Loosestrife (Lythrum salicaria) at the South London Botanical Institute last week. It makes a fine plant for a garden -botanical or otherwise- as long as the soil is moist. Of course the best way to see it is in the wild where it can form extensive stands along streams and ditches. 

 The Walthamstow marshes are part of a ribbon of habitats that stretch along the Lea Valley bringing the wild into the heart of London. Purple Loosestrife grows in abundance. These are a couple of old photos but I'll be over that side of town at the weekend so I'll head for the marshes.