Over het voorkomen van Scilla non-scripta (L.) Hoffmanns. & Link, S. hispanica Miller en hun hybride in Nederland

For the preparation of the distribution map of Scilla non-scripta in the Netherlands, questions had to be resolved regarding indigenity, and hybridization with S. hispanica. In table 1 the main characters of the two parents are shown, derived from Flora Europaea and Flora Neerlandica. The available material in the Netherlands herbaria (c. 150 specimens) could be divided into three groups, viz. true S. hispanica (2 specimens), true. S. non-scripta (60 specimens) and S. hispanica x non-scripta (70 specimens). The colour of the anthers and the ‘graceful bend’ versus ‘stiff rigidity’ of the racemes are unmistakable characters of the parents; width of leaves and shape of perianth are only secondary relative ones; scent, insertion of stamens and length of pedicels appeared unapplicable. In the Netherlands S. non-scripta is not really native, but naturalized in and around ‘stins’ environments, and also along the inner side of the dunes. The northern border of its natural, continental distribution area is in Belgium, south of Bruges and Brussels. S. hispanica x non-scripta was collected already around 1850, but was not recognized. The first hybrids were noted around 1950. Hybrid swarms, already known for years, were reported in 1983. The occurrence of S. hispanica x non-scripta in the Netherlands might be the result of hybridization on the spot, or planting of the hybrid, which subsequently becomes naturalized in or near ‘stins’ environments. If hybridization in the field played an important role, an increase of the width of leaves of herbarium specimens with time is likely, as the leaves of the hybrid and broader than those of S. non-scripta. Table 2 shows the percentual increase of the number of plants with broader leaves per period of fifty years and fig. 2 the onset of hybridization around 1900 in five populations and its gradual increase. A study of catalogues from various bulb-growers in the Netherlands proved that S. hispanica x non-scripta does not belong to their assortment. S. hispanica is often absent from many large populations which became hybrid swarms. Pollination of S. non-scripta in the estates of the inner dunes with pollen of S. hispanica from the bulbfarms in the direct environment of the inner dunes probably can be effected by insects, especially bumble-bees. Finally the distribution maps are given of S. non-scripta (fig. 3, a: data before 1950; b: data since 1950) and of the hybrid S. hispanica x non-scripta (fig. 3, c: data before 1950: ■ herbariumspecimens of the hybrid, • fieldobservations and literature of S. non-scripta; d: data since 1950: ■ fieldobservations and literature of S. non-scripta. S. hispanica and the hybrid, and herbariumspecimens of the latter, • square in which both the hybrid and S. hispanica occur). No distribution map of S. hispanica in the Netherlands is available, because this species does not belong to the Netherlands flora.