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KENTISH MILKWORT

Polygala amarella subsp. austriaca

Polygala amarella-Kentish Milkwort.jpg

The rarest member of the Milkworts, a perennial which grows on chalk grassland and a particular specialist of bare chalk habitats.

  • Rarity: Known from just 2 native sites in Kent, along with 4 introduction sites.

  • Cause of decline: Loss of traditionally grazed pastures and scrubbing over of historic chalk workings

Background

Kentish Milkwort is now only found at 2 native sites, one of which supports perilously low numbers. Fortunately the stronghold population continues to support a healthy population, however this is also showing a picture of decline and we are faced with a real threat of extinction for this iconic species. 

Being an extreme calcicole of open chalk grassland, this species was often associated with historic quarrying activities which maintained the bare chalk environment it requires. Since these activities have largely ceased, most historic sites have scrubbed over and become unsuitable for Dwarf Milkwort. In addition, ploughing, under-grazing & neglect have contributed to the decline of chalk grassland habitats, which in turn has seen the loss of many Kentish Milkwort sites. 

Ecology and Conservation

This short-lived perennial is a small herb, often no more than 5cm in length. The pale mauve to greenish-ish white flowers are borne on several branches. Flowering usually runs from May to July, although it has been known to continue to November in rare occurrences. Reproduction is by seed, which tends to germinate within the same season as flowering or the next, provided there are suitable bare earth niches. 

As with many other chalk specialists, the main threats to the survival of this species include ploughing of chalk grassland, under-grazing and habitat neglect. However, a program of arable reversion & habitat restoration across the Kent Downs is providing the suitable niches required by this species, and with a little help from a dedicated team of experts, we are hoping to return this species to its historic range.

Our work

​Over the last 10 years we have been meticulously monitoring this species and the habitats in which it grows at the native sites. Habitat conservation work has been undertaken at the smallest and most vulnerable colonies, including one which is now likely to have gone extinct.

Many of the historic sites have also been visited and assessed for habitat suitability, and where possible advice given to landowners to help restore the chalk grassland. 

The steering group has been integral to the survival of this species, with regular meetings held to discuss the status of the remaining populations and future work. In 2014, seed was collected from the largest colony at Godmersham and stored at the Millennium Seedbank at Kew with the intention of cultivating for potential reintroduction projects.

Whilst our work has been focussed on keeping the extant sites going, the very real chance of loosing it has pushed our attention to reintroduction to more suitable sites where the populations and management can be closely monitored.

Since 2021, using the collected seed from Godmersham, we have introduced Kentish Milkwort to four new sites within its historic range on the Kent Downs. Given we know very little about seed longevity in the soil, the sites were selected on the basis that there were no historic records of Kentish Milkwort. Other merits required for site selection have included availability of bare chalk, presence of associate species, appropriate management practices & availability of access. 

Recent re-working of the taxonomy of this species has placed Kentish Milkwort in its own distinct sub-species, separating it from the other Dwarf Milkwort populations in the Yorkshire Dales.

 

This means, what was already a rare species, has now become critically endangered, and we are fighting to try and conserve plants in just two remaining sites in Kent.

Monitoring this species is a considerable challenge due to the diminutive size of plants, and as the populations become smaller and more isolated within their sites, it is extremely difficult both to monitor and manage the conservation of the remaining plants.

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