The thesis of Leus can be downloaded from:
That’s a lot of stuff to digest, Henry. Thanks for finding it. Looks very worth reading.
Peter
Thanks Henry. I had only the thesis in a printed book form.
Martin
Llya, I’ve noticed the linseed oil fragrance in Isabella Skinner, too, and attributed it to R. Laxa. The other roses reportedly used in it were a floribunda and an HT. Buck’s Prairie Star has a similar scent to me. It’s reportedly out of laxa X Spinossisima, combined with a number of HTs, and climbers. Kim
Whether Rosa fedtschenkoana, Rosa beggeriana or Rosa laxa are used in a breeding program, it seems to me their potential is a combination of adding toughness and disease resistance along with grey-green foliage to the progeny. Foliage colour is neglected as far as a goal in a breeding program. Yet in the future it will be an important one. This is because Generation X and likely subsequent ones are more interested in plants to decorate their homes rather than gardening with them like the Baby Boomers do. Therefore, they will be interested in plants with novelty foliage that provides contrast to most plants having the usual green foliage to show off their homes.
The question is, using species with grey-green foliage, how can this particular colour be maintained to at least some degree in the F2 or F3 progeny (the F1 progeny will likely be too tall and lack flower quality). It won’t be easy, since grey-green foliage is likely a recessive characteristic.
I developed the first Rugosa (‘Keewatin’) with grey-green foliage by growing seedlings of ‘Henry Hudson’ that were likely self-pollinated. It has been theorized that ‘Schneezwerg’, one of the parents of ‘Henry Hudson’, is a Rosa rugosa x Rosa beggeriana hybrid. This makes sense because this cultivar has superior cold hardiness to most other Rugosa cultivars and also is the first of this type of rose to mature its hips (cold hardy species mature their hips early). The fact that grey-green progeny can be developed from ‘Henry Hudson’ adds credence that Rosa beggeriana is one of the parents of ‘Schneezwerg’.
Rather than cross Rosa fedtschenkoana, Rosa beggeriana or Rosa laxa with modern roses, I’m inclined to first use them to develop species hybrids. Perhaps with North American spcies that has never been done before. I think crossing them with Rosa gallica might also have potential, especially to bring the size of the F1 progeny down while maintaining reasonably good flower quality. In any case, these three hardy and tough species with grey-green foliage should be used in breeding programs much more.
I concur that foliage is grossly underrated. I have noticed more and more use of foliage in gardens over the last 20 years, and I have wondered if other gardeners were acquiring a greater appreciation, or if it was I who was acquiring the appreciation in that i have simply begun noticing such more and more.
Typically, glossy foliage is discussed – not glaucous. I for one wouldn’t mind hanging a nice recurrent flower on a bush with R. glauca foliage. (I wonder what that one would do if crossed with R. fedt…)
In addition, plant texture (on a more macro scale) as caused by leaf size is seldom discussed. i find myself also drawn to the small ferny leaves of many species as well – something seemingly undervalued by most.
Perhaps we should start a new thread on the topic…
I don’t know if a response so much down here will be read. It is a very late comment, but it seems this is just common for us 
I was reading the discussion about some of our cultivars and the parentage. For those interested, the book ‘Rozeninzicht’ 68p with all parentages and much more information (only in Dutch but parentages are readable for anyone)on our roses still can be ordered from anywhere. Price without sending is 10