Basil thyme Clinopodium acinos

Status Amber - Vulnerable and Near-Threatened
Best Time to See May, June, July, August, September
Colour Purple
Habitat Grassland, Arable, Farmland

Basil thyme belongs to the dead-nettle family (Lamiaceae).

It is a short plant (<15 cm), sometimes with a habit of creeping along the ground. It produces whorls of violet flowers with white markings on the lower lip, usually between May and September.


This native lowland plant grows mainly in southern and eastern England and is very rare in Wales, Scotland and northeast England. Its distribution closely follows that of underlying chalk and limestone rock. It is also present in eastern Ireland where is it considered an alien species.


Open habitats in dry calcareous grassland, especially around rock outcrops and also in arable fields, where it is now rare. It can also be a rare casual of 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.


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.

Key threats

The decline of basil thyme is the result 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 and the majority of surviving populations are present 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.

Best time to see

May to September when in flower.