Abstract. About two recent Orchid findings in Wallonia long distance dispersal or overlook syndrome ? [Natural. belges 85 (Orchid. 17) (2004): 89-96]. Two Orchid species, rare in Belgium, have been found in 2004 in new Walloon sites, far from their localities reported so far. Different hypotheses can be advocated to explain their settlement. For Orchis militaris, found in the township of Louvain-la-Neuve, the origin might come through seed dispersal either from natural localities in Wallonia, or from plants cultivated in gardens in the surrounding area. For Epipactis microphylla, a small population has been discovered in the Lesse et Lomme region, which somewhat extends the general distribution area towards the north-west. Observations suggest that the plant might have established already some years ago but has remained unnoticed, and might originate also from long distance seed dispersal. It may also be the case, however, that the species, which is especially discrete and sporadic, has survived for many years in the area, and that suitable conditions resulting from chalk grassland management have allowed for favourable development. The possibility that it has been overlooked for many years in such a well prospected area is discussed, by analogy with the somewhat similar situation of E. viridiflora, discovered as well in the area three years ago.

Key-Words. Š Orchidaceae; Epipactis microphylla; Orchis militaris; New localities; Long distance dispersal; Wallonia.