- Name also: Wild Thyme, Creeping Thyme
- Family: Mint Family – Lamiaceae (Labiatae)
- Growing form: Perennial dwarf shrub. Taproot strong, woody, erect.
- Height: 5–15 cm (2–6 in.). Stem limp, creeping, branched, rooting from nodes, 4-edged; erect flowering branches unbranched or sometimes branched, top almost round, hairy. Also limp, flowerless branches.
- Flower: Corolla irregular (zygomorphic), rose-purple, sometimes white, 6–7 mm (0.24–0.28 in.) long, fused, bilabiate, with straight tube, hairy. Corolla upper lip with notched tips, flat; lower lip 3-lobed, central lobe bigger than lateral lobes. Calyx narrowly campanulate (bell-shaped), bilabiate, lower lip 2-lobed, lobes narrow; upper lip 3-lobed, lobes broadly triangular. Stamens 4, longer than corolla, straggly. Gynoecium composed of 2 fused carpels. Inflorescence a compact umbel composed of axillary whorls.
- Leaves: Opposite, almost stalkless. Blade linear–lanceolate–elliptic, round-tipped, almost glabrous, with entire margins, slightly revolute. Remain green throughout winter.
- Fruit: 4-parted schizocarp.
- Habitat: Eskers, sandy-soiled heaths, rocky outcrops, river banks, meadows, roadsides, riverside sand banks. Sometimes also an ornamental.
- Flowering time: July–August.
- Endangerment: Near threatened.
Breckland thyme is a dwarf shrub that has a strong fragrance and forms mat-like stands, and the base of its stems gets woody as it ages. Its habitat is limited to countries around the Baltic Sea, although it has made extensive inroads into continental Russia. Breckland thyme is the northernmost species in its large genus. It is a very important source of nutrition for large blue and eastern baton blue butterfly caterpillars because they only lay their eggs in Breckland thyme flowers and they only eat thyme. Honeybees like the nectar, making it a good honey plant.
People have used thyme in many ways, from cough medicine to exorcising evil spirits and attracting a bride. Its popularity is based on its pleasant aromatic fragrance. The genus’s best-known representative is common thyme (garden thyme, T. vulgaris), which is used as a culinary herb.
Breckland thyme has two subspecies in Finland, the type species in the south ssp. serpyllum and ssp. tanaënsis in the north. The latter grows only in Inari Lapland and Koillismaa on sandy river banks and sandbanks, and it has slightly broader and yellower leaves and larger flowers than the southern type species. Broad-leaved thyme (larger thyme, T. pulegioides) is an ornamental and escape in Finland, and it differs from Breckland thyme only with regards to its stem, which is smoothly haired along its edges. It also lacks the flowerless branches that are characteristic of Breckland thyme.