The area supports some of the largest colonies of marsh orchid in Essex and Hertfordshire. Dactylorhiza cruenta, the Flecked Marsh Orchid, is a palearctic orchid. Other species recorded are Yellow Flag Iris, Ragged Robin, Marsh Marigold and Southern Marsh Orchid. In some of the dune slacks there are populations of marsh orchid and common twayblade. Boggy areas support cotton grass, marsh orchid, sundew and bog asphodel. One of the rare plants, the straw yellow Early Marsh Orchid (Dactylorhiza incarnata subsp. In Switzerland the broad-leaved marsh orchid is also quite widespread. Southern marsh orchid, meadowsweet and yellow loosestrife are among the plant species that grow here. In Germany the broad-leaved marsh orchid is widespread but with several gaps. The broad-leaved marsh orchid has a karyotype of two sets of forty chromosomes. The broad-leaved marsh orchid is usually tall, though some specimens may reach . In 1828 Ludwig Reichenbach described the broad-leaved marsh orchid as "Orchis majalis". The broad-leaved marsh orchid ("Dactylorhiza majalis") is a terrestrial Eurasian orchid.