Nationally rare Purple Gromwell and the dilemma of name changes

Purple Gromwell, Aegonychon purpureocaeruleum, a nationally rare plant found in North Somerset
Purple Gromwell, Aegonychon purpureocaeruleum, in Cheddar Wood, Somerset in spring 2019. The above flowers show the changing colour from reddish-purple to blue. © Karen Netto (Andrews)

The nationally rare plant Purple Gromwell is found locally as a native, woodland plant. The Green Brothers mention it as locally common in the Axbridge-Cheddar area of the Mendips in their Atlas Flora of Somerset. This was the location of much of my childhood botany, so its ongoing survival is of personal concern.

Purple Gromwell’s local and regional statuses are shown in the table below:

Rare Plant Status

Great Britain:Least Concern (LC)
England:Least Concern (LC)
National Status:Rare
South Somerset (VC5):Scarce
North Somerset (VC6):Not Scarce
Table 1: Rare Plant Status of Aegonychon purpureocaeruleum, Purple Gromwell

Historical Records

The plant was first recorded in Britain near Taunton in South Somerset in 1670. Since that early record, it has declined in South Somerset to today’s scarce status. It is more readily found in North Somerset. Roe observes that it is a plant that may easily be overlooked. It is shy in flowering and not conspicuous in leaf.

Recent Records

The Online Atlas of the British and Irish Flora states that the population has been more or less stable since 1930. Neglect and shading in unmanaged woodland have caused some past populations to disappear. There is a risk that the status of native plants may be obscured by an increase in garden escapes since 1962. The Wild Flowers website states that native Purple Gromwell is now very rare and getting rarer. Its distribution is localised in South West England and Wales.

Latin Name Changes

Tracking the history of this plant can also be obscured by its Latin name changes. Unusually, it has been known by fewer vernacular names than Latin names. The names of Purple Gromwell or Blue Gromwell reflect the changing colours of the flowers. Stace updated Purple Gromwell’s name from Lithospermum purpureocaeruleum to Aegonychon purpureocaeruleum in his Fourth Edition of New Flora of the British Isles. It has also previously been known as Buglossoides purpureocaerulea. Kew’s Plants of the World Online lists a total of 12 synonyms for the species known from Europe to North Iran.

A New Type Genus

Eminent Czech botanist, Josef Holub, proposed Purple Gromwell as a new type genus in 1973. His proposal for Aegonychon was adopted by Flora Iberica in 2012. Cecchi’s 2014 taxonomic paper resurrected the view that Aegonychon should be a separate genus. The previous genera were considered too diverse. The Aegonychon genus is restricted to a classification of 3 woodland plants.

Name Origin

Holub did not invent the genus name. Aegonychon was already in existence. Online research suggests that the name was created by one of two botanists by the name of Gray. Asa Gray (1810-88) is considered the father of American botany. The alternative supported by Brummit & Powell’s Authors of Plant Names database (1992) is British botanist and mycologist, Samuel Frederick Gray (1766-1828).

Name Meaning

What does the genus name mean? According to Quattrocchi, Aegonychon comes from the Greek aigonyx/aigonychos meaning goat-hoofed. Like Linnaeus’ original name of Lithospermum (stone seed), it is inspired by the appearance of the seeds. Onyx/onychos suggests a claw nail resemblance. The epithet purpureocaeruleum has remained constant. It combines purple and blue to describe the changing colours of the flowers.

Scientific Rigour

Modern taxonomists understandably want precision based on the latest DNA research, evolutionary knowledge and morphological analysis. Aegonychon‘s 1973-2019 timeline demonstrates that they are not hasty in revising a plant’s Latin name. Nevertheless, it is much easier to consult plant records if Latin names remain constant. The issues relate to application rather than scientific rigour.

Application Issues

There is already a potential muddle in separating native plants and garden escapes for plant recorders. Horticulture resists name changes for even longer than taxonomists. Go to any garden centre and you will see the time lag. Updating databases can be time-consuming, error-prone and expensive. Two Latin names can be in simultaneous use (sometimes more when taxonomists are in dispute). It is confusing for those who have known several names for the same plant in their lifetime. Different printed and online resources can conflict. Authoritative sources are expensive and often inaccessible for the learner, especially for that important next generation of young botanists. Simple, definitive answers are hard to find.

Which Latin?

Staggered international acceptance undermines one of the key advantages of Latin names. It leaves taxonomists no longer speaking the same Latin.

Broken Links

Purple Gromwell, Aegonychon purpureocaeruleum
Purple Gromwell, Aegonychon purpureocaeruleum

Tracking the historic locations of rare plants is important to Red List status. Excessive name changes break and obscure record links. Does this pose the risk that a rare, but easily overlooked plant might be neglected at a critical time for its survival? I hope not.

According to Grigson, everyone should try to see Purple Gromwell. He compares its beauty to that of Gentiana verna, the Spring Gentian. The flower changes from reddish-purple to an intense blue. The blue fades quickly if picked and the leaves droop. It is a flower best admired in the field. Long may it continue to flower in the Mendips for future generations.

References and Further Reading

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