Enige aantekeningen over het geslacht Crataegus L. in Nederland

A preliminary systematic study of the genus Crataegus L. in the Netherlands resulted in the fact that at least 3 taxa can be distinguished, viz. the species C. monogyna Jacq. and C. oxyacantha L., and the hybrid C. calycina Peterm. X C. oxyacantha L. The hybrid was not yet known from this country; it is found in the NE part of Drente in hedges around wet pastures on a clay-formation deposited in the Riss-glacial period.