I read with interest your account (Malvern Gazette, February 4) of the threat to black poplars from black poplar scab and share the article's concern.

Unfortunately your headline is not strictly accurate and nor is the statement in the article that: "The black poplar, Britain's rarest native tree..."

National rarity in Britain is usually taken to mean that a plant species occurs in 15 or fewer 10 x 10 km squares (known as hectads). Plants are described as 'Nationally Scarce' if they occur in 16 to 100 10 x 10 km squares in Great Britain.

Black poplar is known to occur in 601 hectads in Great Britain, so it is neither 'Nationally Rare' or 'Nationally Scarce'. This information is available from the New Atlas of the British and Irish Flora, published by Oxford University Press in 2002.

I have counted no fewer than 25 tree species which are known to be Nationally Rare or Scarce according to the Joint Nature Conservation Committee (The UK's umbrella conservation quango) and I may have missed some. So black poplar is not a rare plant nor the rarest tree in Great Britain.

This list of rare or scarce trees includes many trees related to the mountain ash (they are described as whitebeams), the Plymouth pear, several willows, large-leaved lime and Plot's elm. Some of these species are represented by fewer than 100 trees, much less when compared with the 10,000 or so specimens of black poplar noted in your account.

You are, however, in good company as black poplar is often, or even usually, described as a rare tree and the rarest of British trees.

For example, an information note, published on the web by the Forestry Commission (who should know about these things) in May last year, described the species as Britain's rarest native tree species!

Dr Peter Alma, Teme Avenue,

Malvern.