Sulphur Clover, Trifolium ochroleucon, on a road verge in South Norfolk.

It is always good to find an unexpected plant while out on a walk or cycle ride. Yesterday’s treat was Sulphur Clover, Trifolium ochroleucon, growing on a road verge in South Norfolk. I was on a bike ride with a couple of friends and we were heading home from a lunch stop at Hedenham church when I noticed a large patch of pale yellow clover flowers on the road verge. We stopped and turned back (very easy to do on a bike) and took a closer look.

I say “unexpected” because I have cycled on this road many times, but mostly in winter, so I have never seen Sulphur Clover growing there before. But the habitat is ideal: clay soil and a wide grassy verge, which is managed as a Roadside Nature Reserve. We found further patches of Sulphur Clover on some of the verges as we headed north towards Shotesham.

Sulphur Clover is a clump forming perennial in the Fabaceae (Pea family; formerly Leguminosae) and flowers in June and July. It likes alkaline soils, usually boulder-clay, but can sometimes be found on chalk. It grows on trackways and the borders of woods and in old meadows and pastures but, like the Green-winged Orchid I wrote about earlier this month, it has declined with agricultural “improvement”, whether by ploughing or an excess of nutrients from artificial fertilisers, which encourage coarser grasses to grow at its expense. Road widening has taken its toll and neglect can be damaging too, if grass is not cut or scrub shades it out (note 1).

Sulphur Clover has its stronghold in East Anglia and roadside verges are particularly important for its survival.

Further afield, Wikipedia describes the plant as “fairly widespread throughout the rest of Western and Central Europe, and it has also been recorded from Iran and North Africa’, although the same pressures will apply, as agriculture becomes more intensive and the world is “developed”.

In Norfolk in recent years the plant has had some help. Norfolk Wildlife Trust has worked with local councils, the Farming and Wildlife Advisory Group (FWAG) and private landowners to spread green hay from road verges where the plant has flowered and set seed, to introduce it (and other rare plants) to new sites, as described in the Diss Mercury from July 2008. Happily, the work has yielded results.

Sulphur Clover makes a well behaved and lovely garden plant too. The BBC Gardeners World website has information on growing it, ideally on chalky soil in dappled shade. It is hardy to below -20 Celsius. Normally you can buy the seed from Emorsgate Seeds, though I notice it is out of stock at the moment. Chiltern Seeds also sell it.

Sulphur Clover is attractive to insects and Garden Bumblebees (Bombus hortorum) were visiting the plant that I photographed.

Stopped in our tracks on a bike ride, by Sulphur Clover.

Notes

Note 1 – The Online Atlas of the British and Irish Flora gives details of how the plant can suffer from tidying, excess competition or neglect – see the tab “Other Accounts”.