On 31st July 1990 seven plants of a small felwort, Gentianella amarella (L.) Boerner, were discovered by the writer growing in short, sheep-grazed Festuca – Sesleria grassland at Kettlewell. Unlike our usual felwort which has blue flowers, these plants had the corolla white on the inside with a maroon outer surface and fitted exactly the description of Gentianella amarella ssp. septentrionalis (Druce) N. Pritch. This determination was subsequently confirmed by Dr Noel Pritchard, BSBI referee for Gentianaceae.
Source: wiktionary