DHBlog008 · An article by Robert Sharp
The plant in question is Persicaria nepalensis (Nepal Persicaria), a bird-seed alien from tropical Asia and naturalised in northern Italy. Whilst surveying Boscombe Chine for bryophytes a couple of weeks ago, Mark Dale found some plants growing at the base of a wet bank. Not being instantly recognizable, we zapped it with PlantNet but the result, Persicaria capitata (Pink-headed Knotweed) was unconvincing. We eventually found P. nepalensis in the BSBI handbook (No. 3) right next door to P. capitata. The distinct shape of the lower leaves and lack of black marking making a much more convincing case. After some discussion over how to describe the leaf shape, Robin Walls did a little sketch.
According to Stace, P. nepalensis occurs in Somerset, where it was first recorded at Yeovil, South Hampshire, and Dorset. While there are no records for Dorset or South Hampshire on Living Record as of October 2022, the BSBI database concurs with Stace for records pre-2010. Since then, there has been no sign of it and most of the records are actually pre-2000. It looks as if, in Dorset at least, it has all but disappeared.
This seems a little odd in an age when alien species from warmer climates appear to be invading the country so perhaps the explanation is under-recording? The BSBI database shows that it was last seen in the following locations: Wareham (SZ98I, 1 record pre-2000); Canford Bottom (SU00K, 1 record pre-2000); Moreton (SY88E, 2 records pre-2000); Abbotsbury (SY58S, 1 record pre-2000); Blandford (ST80Y, 1 record pre-2000); and Bournemouth (SZ19A, 2 records pre-2010). Akeroyd (BSBI Handbook No. 3) tells us it can found in garden centres. He mentions Hillier’s Arboretum near Romsey and even the Royal Botanic Garden in Edinburgh. I did a quick check on the RHS website and was surprised to find it is sold by at least 1 garden centre in the UK, but this is nowhere near Dorset. Perhaps someone recognises the plant and has seen it more recently?
