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Basil Thyme

Clinopodium acinos

Basil Thyme used to be picked as a substitute for thyme, but it is now too rare to pick. Its distribution closely follows that of underlying chalk and limestone rock.

How to spot it

Like other members of the dead-nettle family, Basil Thyme is popular with bees and insects. At only 15 cm high, it produces whorls of violet flowers with white markings on the lower lip. Common Calamint and Wild Basil are closely related but are larger and with taller more dense flower spikes.

Where to spot it

Basil Thyme grows mainly in southern and eastern England and is very rare in Wales, Scotland and northeast England. It is also present in eastern Ireland where is it considered an alien species. It grows in open habitats in dry grassland, especially around rock outcrops and also in arable fields, where it is now rare. It can be found in quarries and waste ground where calcareous rocks and lime-rich soil has been exposed and roads and railways where lime has been applied. In Ireland, Basil Thyme grows on sandy and gravelly soils.

How’s it doing?

Basil Thyme is unfortunately in decline because of more efficient methods of weed control almost causing its complete extinction in arable habitat. Basil Thyme is only present on less intensively used arable land and in chalk and limestone grassland. Threats to grassland populations include the lack of bare ground which is required by this species to aid seed germination. In Ireland, sand and gravel extraction are the main causes of decline.

It is classified as ‘Vulnerable’ and is included as a species “of principal importance for the purpose of conserving biodiversity” under Sections 41 (England) and 42 (Wales) of the Natural Environment and Rural Communities Act 2006. Basil Thyme is also noted on the Scottish biodiversity list of species of principal importance for biodiversity conservation in The Nature Conservation (Scotland) Act 2004.

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