Polygala amarella (or P. amara), commonly known as dwarf milkwort or Kentish milkwort,[1] is a plant of the family Polygalaceae. A European native, it grows on chalky grass land and limestone mountain pastures.
The plant typically grows up to 20 cm tall and has small, blue-purple flowers that bloom from May to August. The leaves are alternate, narrow, and smooth-edged, and the stems are slender and wiry.
This species is very similar to chalk milkwort but can easily be separated from it by the rosette leaves being basal in dwarf milkwort, but slightly raised on the stem in chalk milkwort. Also, dwarf milkwort has a bitter taste (not so in chalk milkwort). In dwarf milkwort the inner sepals are longer than the petals.[2]
Widespread throughout Europe, especially in the Alps, but currently only found in Kent and Yorkshire in the UK, where it's found at the periphery of its range. Mostly found on chalky grasslands of Kent on the North Downs, and on limestone outcrops in the Yorkshire Dales.
The Ellenberg values: L=9, F=6, R=9, N=1, S=0 which means that the plant grows in full light, moist, basic, infertile soils with no salinity.it's a short lived polycarpic perennial. The reproduction is solely by its seeds which have a small oily appendage (known as the elaiosome) which aids dispersal by ants. It is believed the Kent population is shorter-lived than the Northern population. The seeds persist in the soil for less than a year.
Polygala amarella has traditionally been used in herbal medicine.[3]
In 2009 it featured on a first class Royal Mail stamp in the series "Endangered Plants".[4]