Surprising find in Cambridgeshire

Marsh Pennywort leaves (they are peltate
 like a Nasturtium leaf)
Image courtesy of Floral Images
 http://www.floralimages.co.uk/page.php?
taxon=hydrocotyle_vulgaris,1

Just in from Cambridgeshire co-recorder and BSBI Field Meetings Secretary Jon Shanklin:

"Cambridgeshire botanists are out recording across the county for lots of projects - Atlas 2020, Fenland Flora, Cambridgeshire Flora and a Natural History of Cambridge. 

"This last prompted me to see if a local golf course would let me have a quick look round as I was passing. It proved a worthwhile diversion - in a marshy area I found Marsh Pennywort Hydrocotyle vulgaris, apparently last recorded in the area by Relhan in 1820 on "Trumpington Moor" - Trumpington is just a mile from the site. 

Marsh Pennywort in flower
Image courtesy of Floral Images
http://www.floralimages.co.uk/page.php?
taxon=hydrocotyle_vulgaris,1

"Although not yet rare in Britain & Ireland, today it is only known from a few SSSIs in Cambridgeshire, and is assessed as Near Threatened on the England Red List, so the find clearly needed further investigation. A return visit allowed a chat with the director of the course, who recounted an interesting story. 

"The golf course had been created from farmland about 20 years ago, and originally had three lakes. One of these proved a bit more of a hazard than was desirable, so had been partially filled with soil obtained from British Sugar at Bury St Edmunds, and then landscaped to form a marshy depression. 

"The plant had been spotted previously by an old lady golfer, who had exclaimed "Fen Pennies - I haven't seen those since I was a child". The origin of the plant however still remains a bit of a mystery - the soil from Bury would presumably have been sugar beet washings, so an unlikely source, and recovery from the seed bank after 200 years seems equally unlikely. 

"Maybe we should be looking more closely at other marshy sites where it has been historically present!"