Het onderscheid tussen Cardamine flexuosa With. en C. hirsuta L

The differences between Cardamine hirsuta L. and C. flexuosa With, have been analized from fifty specimens of both species in the collections of the Rijksherbarium in Leiden. The most distinguishing characters are: 1. the stem of C. hirsuta is usually shorter (fig. 1, a); 2. the base of the stem of C. flexuosa is usually densely hairy (87%, glabrous + scarcely hairy 13%), that of C. hirsuta is usually glabrous or scarcely hairy (89%, densely hairy 11%); 3. the basal leaves of C. hirsuta are usually in a compact rosette (67%), C. flexuosa usually has not such a compact rosette (67%); 4. C. flexuosa usually has more cauline leaves (fig. 1, b), this is an important character; 5. the siliquae of C. hirsuta usually overtop the flowers more (fig. 1, d); 6. the angle between the young siliquae of C. hirsuta and the stem is usually smaller (fig. 2); 7. the flowers of C. hirsuta have usually 4 stamens (80% 4 ♂, 18% 5 ♂ and 2% 6 ♂), those of C. flexuosa have usually 6 stamens (97% 6♂ and 3% 5 ♂). Outside the specimens counted I have rarely seen flowers of C. flexuosa with 4 stamens. It is important to count the stamens of a number of flowers on each plant. The number of stamens is the most important character I have found. All the specimens of the collections were examined for flowering-time and locality. Fig. 3, a-b shows the difference in flowering-time. The localities are divided into 5 categories: 1. in the dunes, 2. along roads/dikes, 3. along streams and ditches, 4. in woods, parks and country seats, 5. on waste places. The two species can grow in the same place, but fig. 3, c-d shows a clear difference in habitat. In the literature the existence of hybrids is mentioned, but I did not find one in the examined material.