Common Spotted-orchid possesses one very attractive variety and two sub-species, each with a limited distribution. The normal form is described below; the other forms are described and illustrated in the next species account (Common Spotted-orchid - varieties and sub-species).

Can grow up to 70cm tall in sheltered locations. There are numerous narrow, pointed basal leaves and three to five clasping stem leaves. The leaves are usually spotted or blotched with purplish-brown marks; there is considerable variation in these markings. The bracts are pointed and longer than the ovary. The flower spike of numerous pale lilac or pink flowers is closelypacked and tapers at the tip. The lateral sepals are spreading, the dorsal sepal and upper petals forming a loose hood. All are marked with lines and dots. The lip has three well-defined lobes, the lateral lobes being rhomboidal in shape, and the central lobe longer and triangular. The lip is marked with a symmetrical double loop enclosing a series of lines and dots, while the spur is straight and slender - in contrast to the fat, conical spur of the marsh-orchids. White flowers with yellow pollinia alb are not uncommon, but can be confused with very faintly marked flowers where the bursicles around the pollinia are pale mauve.
CONFUSING SPECIES: Heath Spotted-orchid has narrower leaves with smaller spots and a more triangular flower spike. Its flowers have a broader lip with a small central lobe and smaller markings which extend across the whole lip surface and do not form a distinct double loop.
HYBRIDS: Hybridises with all three forms of Fragrant Orchid, also with Frog Orchid, rarely with Early Marsh-orchid and more frequently with Southern, Northern, Western and Narrowleaved Marsh-orchids. The hybrid with Heath Spotted-orchid has been reported but is difficult to identify with certainty. Photographs of most of these hybrids are shown here.
Widespread in calcareous and neutral grasslands, in open woodlands, in old quarries, on railway banks and road verges throughout Britain and Ireland. It avoids truly acid soils, but has proved capable of colonising waste ground and abandoned industrial sites.Pollinators include hoverflies, female Cuckoo Bees, Buff-tailed Bumblebees and the beetle Dascillus cervinus. Seed-set is efficient, and plants also multiply vegetatively to form clumps.The plant can rapidly colonise suitable habitat.