07 June, 2013
This week’s blog has been written by Jan Tapson. Jan is one of the many volunteer rangers who assist in the management of Holyrood Park, and has recently become involved in the ongoing wildlife surveys.
The park is home to many rare and endangered species, including adder’s tongue, sticky catch-fly and purple milk-vetch. Jan has undertaken to monitor the purple milk-vetch population.
Purple milk-vetch (Astragalus danicus) is a native species in the vast pea family, which includes gorse, broom, beans, clovers and vetches. It has dark brown pea pods. Its Latin name Astragalus alludes to the shape of the seed, which is similar to one of the bones in an ankle.
This is a diminutive trailing plant with composite heads of purple flowers and vetch-like leaves. These lack the terminal ‘tendrils’ found on other members of the pea family – which means it does not rely on clinging onto and climbing other plants for its survival.
It exists best on calcareous soil which has been exposed to grazing or gentle erosion by other means – places which allow it to compete with thyme, yarrow, clover, vetches and pineapple-weed, all of which colonise similar situations.
Purple milk-vetch was once common, and considered an important component of cattle feed, enhancing milk production – hence its name. It is a favourite food of bees and other insects.
Since enclosure laws were introduced in the 1800s and more recent agricultural improvement it has become increasingly rare, now largely confined to the east coast of the UK.
In 2007 it was added to the ‘endangered species’ Red List (Conservation Act of 2005) due to its rapid decline.
Holyrood Park is home to a significant population, which survives in seven locations. Yearly surveys have not been carried out since 2009, so this is an important project to ensure the populations remain sustainable.
Kate Greenaway, a famous children’s book illustrator during the Victorian era, wrote and illustrated a book called The Meaning of Plants. Of milk-vetch, she writes, ‘Your presence softens my pain.’
Thankfully due to the effort of the ranger service this plant will continue to be present in Holyrood Park.