09 October 2012

Small Balsam along the Afon Llwchwr

A small population of this alien plant was noted in tall-herb vegetation near a stream passing an old farm house above Pontarddulais today. The leaves of Small Balsam (Impatiens parviflora) are similar to those of its larger relative, but the delicate, pale yellow flower, with a short triangular spur (hidden in photo) and narrow capsules make identification straight forward.
It was first noted growing wild in the UK in 1823 in Surrey and appeared in Glamorgan c1907, when H.J. Riddelsdell found it on the banks of the Afon Llwchwr between Pontarddulais and Garn-swllt. Unlike Indian (or Himalayan) Balsam (I. gladulifera), its distribution seems stable and much more restricted in South Wales.
Mines of the agromyzid fly Phytoliriomyza melampyga were found on both species of balsam at this site.

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