Isn't it a wonderful scent? I adore P. schlimii for the fact that its scent brings back a lot of fond memories. It's so sweet, reminds me of the softer, sweeter tones of wild roses or certain rose perfumes.
As mentioned, the scent carries over into some of its hybrids. Primary hybrids or near primaries are the ones that tend to have the strongest fragrance. P. Hanne Popow and similar crosses like P. Seymour Tower are quite often nice and fragrant. One of my favorites is P. Eumelia Arias, because the flowers are quite large, nicely colored, and to add fragrance to that, even if it's not terribly strong, is icing on the cake. Crosses with the "greenies" tend to be less fragrant, but I know crosses like P. Carol Kanzer sometimes at least have a faint scent.
Obviously, different clones are going to have different propensities to being fragrant, and the plant's overall health as well as the growing conditions can affect the strength.
