154 plant species, chosen at random, and collected in the Netherlands were investigated cytologically. The chromosome numbers determined were compared with data known from other countries.

The Orchids in the Netherlands have been subjected to a cytological investigation. The division of the genera Orchis (L.) Klinge into two new genera: Orchis (L.) Vermln. and Dactylorchis (Kl.) Vermln. (Vermeulen, 1947), could be confirmed. In Listera ovata (L.) R. Br. the diploid chromosome number is 34. Deviating numbers 2n = 35 and 2n = 36 were counted. Because aberations in chromosome number do not cause morphological differences these aberations seem to be unimportant. Out of the material investigated it might be concluded that for the moment it does not seem to be correct to consider Dactylorchis fuchsii (Druce) Vermln. as a separate species besides Dactylorchis maculata (L.) Vermln. It seems more likely that D. fuchsii and D. maculata represent two types within a complex‐species.

The chromosome numbers of 32 plant species from Spain and S. France, all collected in natural habitats, were determined. Voucher specimens have been deposited in the Utrecht Herbarium.

The chromosome number of 118 plants belonging to 108species collected in the wild in Syria has been determined. Notes on some species are given.

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