Common Gromwell is a bushy plant growing to about 1 meter in height and it produces yellowy green flowers.
I first recall seeing this plant growing at a place that I regularly visited called Foulden Common in Norfolk. I had been going there for several years with students and then one year I noticed just one plant of Common Gromwell growing on the Common…. I think that would have been around 1985 which was several years after I started using this site. It was growing quite close to the entrance and there was just one solitary plant.
As time passed, year on year the population grew and spread further into the common. It was never that populous but from that one plant eventually the number developed to about 20 or 30 individuals. The habitat was right for it as Foulden had an alkaline soil and there were quite a lot of trees and shrubs dotted about in the grassland to provide some degree of shade. I suspect that the first plant probably was transported there as a seed on the boots of a visiting rambler or dog walker. The seeds are quite distinctive, they are shiny little nutlets and white in colour.
The name Gromwell relates to these seeds, it comes from the Old French name Gromil (now Grémil) which then led to the English Gromwell. This is a combination of two words gré (grey, the colour) and mil (for millet seed) which gives grey millet the colour of the nutlets. The seeds tend to be grey to start with and become more white as they mature, you can see examples of both in the slide show below.
Recently I came across lots of plants in the Forest of Dean growing along a track leading away from an area known as Speculation…. The Forest of Dean was and still is to a small extent an area of iron and coal mining, Speculation was a coal mine but little remains to indicate this today. Perhaps the main feature is the old railway tracks, now used by walkers and cyclists. It was along this track that the Common Gromwell was growing. I suspect its presence might have something to do with the soil along the old railway track being alkaline, due to material used to make up the substrate. Possibly limestone chippings. Most of the forest soils are acidic. All the photos here were taken in the Forest of Dean in mid September. Most of the plants only had the little nutlet/seeds showing there were only a few which still had some flowers in bloom.
Common Gromwell is not actually that common, its distribution obviously links to its preference for alkaline soils, as can be seen in the distribution map.
There is another Gromwell species which is Purple Gromwell, although it is more blue than purple and this can also be found in open woodland situation.