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Plant Allergy Expert Changes Course to hear Henrik Sjöman’s Barcham Seminar

Last Updated:  02/11/2017

Just a week after California-based plant allergy expert Tom Ogren led a seminar on the subject at Barcham Trees' nursery, he was back at the Ely, Cambridgeshire, venue in late October, having altered his UK itinerary to listen to and exchange views with renowned Swedish tree researcher Henrik Sjöman.

Accompanying Ogren was Nigel Clarke of Queux Allergy-Friendly Plants, whose Guernsey nursery ( offers plants with ratings on the Ogren Plant Allergy Scale (OPALS®) to enable purchasers to make informed choices based on their allergen potential. Both men are trustees of the not-for-profit organisation Safe Gardening (

Henrik Sjöman, Tom Ogren and Nigel Clarke were welcomed to the event by Jaime Bray, vice chairman of the Arboricultural Association, and Barcham's Keith Sacre. More than 30 delegates heard tree-hunter Sjöman discuss his travels in China, central and eastern Europe and North America as part of his quest for rare and unusual species which may have the potential to become alternative choices as urban trees in Scandinavia.

Tom Ogren commented:

"It was well worth making a detour to listen to Henrik. We are both heavily involved in tree selection and it was stimulating to hear about his perspective and the criteria he uses in the selection process".