Late June is the peak flowering time for one of my favourite ‘weed’ groups, the Willowherbs.

Originally plants of arable fields and woodlands, at least five different sorts have found a home around town, squeezing life from cracks and crevices around buildings, and a close look will reveal delightful, four-petalled pink flowers sat on top of long seed pods.

There are fourteen different Willowherbs in the UK; one complication is that the different species are so closely related they can cross breed and there are about 40 known hybrids. The true species range from the tiny Alpine Willowherb of the Highlands of Scotland to the banks of dark pink Rosebay Willowherb that dominate urban waste ground and railway embankments across the south of England. The SVBG has found nine different species locally, five are living in the town, but they can be very tricky to tell one from another and so we expect to identify others as we take a closer look at some sites.

All of the local species have the characteristic four pink to pale purple petals on each flower. The flowers sit on top of the ovary which becomes an elongated seed pod. When ripe, the pod splits open and releases the fluffy seeds which are blown on the wind to disperse them, rather like the seeds of Willow trees, hence the common name.

Because they are growing in cracks and crevices, most of the town’s Willowherbs are quite small, but you can find the largest species, Great Willowherb growing to its full 1.8m (6ft) in several places. Its Latin name Epilobium hirsutum translates as ‘on top of the pod (referring to the flower) and hairy’, which it is. Its other common name is Codlins and Cream, Codlins being apples. The pink flower being the apple with the stigma a splodge of white cream in the middle.

There is another hairy or Hoary Willowherb. This tough little character can survive in very harsh conditions such as on top of the walls around local churchyards and even down on the beach. Its Latin name of Epilobium parviflorum means small flowered, and they are only about 6mm across.

The fluffy seeds get everywhere and they have been carried around the world as nations trade with each other. One of the commonest species found in Sidmouth is the American Willowherb which was first recorded in England in late Victorian times, although it may have arrived from the colony much earlier. If you see a much branched Willowherb with red stems it is probably the American species.

Willowherbs are great for wildlife; Rosebay and Great Willowherb are listed on the RHS British wildflowers ‘Plants for Pollinators’ list. In addition to providing food for pollinators, the caterpillars of numerous moths, including the Elephant Hawk Moth, feed on Willowherb leaves. So, if they have taken up residence in your garden, it might be a good thing to allow them to stay.