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In spinach the breeding of hybrid varieties is attractive because this may result in a heterosis and/or a transgressive effect . Resistance to downy mildew [Peronospora spinaciae (MONT.) DE BY] and against mosaic (Cucumis virus, 1) can be combined rather easily, since in both cases the resistance depends on one dominant gene . Besides a hybrid variety excludes the growing of later generations .However, a careful removal of all pollen-producing plants demands so much labour that a production of hybrid seed on a commercial scale involves great difficulties . The creation of an entirely female variety would be a solution for this problem . An outline has been given of the way in which such a variety can be developed, starting from purely female and from intersexual plants .It is possible to simplify the production of hybrid seed by using a round-seeded female parent and a prickly-seeded male parent . Moreover this will prevent errors all plants can then be harvested and threshed at the same time and in cleaning the prickly seed can be separated mechanically from the round-seeded commercial seed . The use of a prickly-seeded male parent will be an extra check on the possible growing of later generations by others .