The Scottish Rock Garden Club....... For People Who Love Plants
I can't answer the question specifically Wim, but it is always worthwhile to try some cuttings in water. Even x Boydii and reticulata will root this way and then I pot then into a gritty mixture when they have about 1cm of visible root. Salix from seed are very slow and the seed has almost no viability over time as well as appearing just as little bits of fluff, not easy to see if seed is actually there anyway.If I haven't contacted you about your Pinguicula seed in the past, it was because nothing germinated, but just this week, there is one seedling of P. grandiflora! I'm very pleased as you can imagine. It is all of 2mm across.
To add a little to the above question, willow cuttings root best in willow water, i.e. water in which willow twigs have been left to soak for a few days. Any species can be used, such as ordinary "pussy" willow or a golden willow or the twisted one or I use S. melanostachys because that's what I have. I leave the twigs in the water for about 4 days and remove them and throw them away before they root. Then I put my preferred cuttings into that water, topping it up as necessary. Most species will be rooting within a week.
Wim, so far there is just the one seedling and I see I sowed both species in January 2009, so getting on for 2 years ago! The one is at the side of the pot where the (originally dried, apparently dead) spaghnum I sowed them on, hasn't become so thick. Otherwise, both pots are bushy and green with new spaghnum, like a thick, shagpile carpet, maybe too think for the tiny seedlings to penetrate?