Abstract. Devillers, P. & Devillers-Terschuren, J. - Evolution of the Epipactis phyllanthes G.E. Smith stations in the Fort de Soignes (Belgium) [Natural. belges 80 (Orchid. 12) (1999): 282, 311-320] . Two stations of Epipactis phyllanthes have been known in the Fort de Soignes, central Belgium, Brussels region, since 1982 and 1988, respectively. They are the only ones known in Belgium and on the European continent between Denmark and southwestern France.The smallest one is now limited to a thin, beech-shaded, fringe of alders along an eutrophic lake and comprised 9 plants in 1999. The biggest station is developed along the edges of a main traffic artery, under a very dense canopy of beeches, on calciferous Ledian sands. An exhaustive 1999 census revealed 233 flowering stems, up from 122 in 1988, which makes it one of the largest known colonies of the species, and perhaps the largest on the continent. The morphological characters of the plants, which are cleistogamic and correspond closely to variety degenera Young, are discussed. Between 1988 and 1999, there appears to have been a shift towards a greater prevalence of larger size-class plants with more rounded leaves. Risk factors and conservation measures are discussed.

Key-Words: Orchidaceae, Epipactis phyllanthes, conservation biology, habitats, Belgium, Brussels Region.