Hybrids between wild and cultivated carrots in Danish carrot fields

It is well known that wild carrots may pollute the seed crops of cultivated carrots, but whether cultivated carrots can also disperse pollen and seed, and thereby introduce genes into wild carrot populations, is only little described. In Denmark, there is no commercial seed production of carrots, and as biennials they should normally not flower before harvest of the roots. Still, flowering individuals can be found in most Danish fields, and sometimes in very high numbers. At least 75% of the flowering plants are male fertile, with ca. 83% of the pollen being viable. More than half of the plants produce seeds. Pollen and seed dispersal from fields into wild carrot populations is probably rather frequent in Denmark. A closer inspection of the morphology of flowering plants indicate that some of these (2-60%) are bolters of pure cultivar origin, as indicated primarily by orange root colour. The remainder is probably first or advanced generation hybrids between wild and cultivated plants, as indicated by their white roots and combinations of morphological characters from either plant type. Some of these hybrids are imported to Denmark together with the sowing seed, as indicated by significantly different frequencies of bolters with white roots in different carrot cultivars tested in the field.