They are both Japanese dappled/variegated willows but apparently if you are lucky, then they are both the 'Flamingo' variety as opposed to 'Hakuro Hishiki'. I never heard of the 'Flamingo' when I bought mine in 2004 and I don't honestly think it was available at that time. Frankly, I've had no problems with my two 'Hakuro Hishiki'. Salix integra "Flamingo" USPP 17,490 Foliage: Spectacular deep pink foliage in Spring and this cultivar retains a strong pink color throughout the growing season. Produces an enormous range of contrasting colors in the garden. A much improved sport of Salix integra 'Hakuro Hishiki'. Leaf scorch is not a problem as both branches and foliage are much stronger than those of Hakuro Nishiki.

OK - tree-form or standard dappled willows are grafted onto a different willow species, usually goat willow, Salix caprea. The dappled willow shrubs (Salix integra) are multi-stemmed - they do not produce a single, distinct trunk - and you can train these puppies for the rest of your life and you will never get a satisfactory tree-like specimen. If you want them like that, purchase them already grafted. Plants that grow happily outdoors in the northern hemisphere - like the willow - do not grow well as houseplants. There is insufficient light and humidity indoors and the temperature is too even. They NEED that winter cold period to achieve proper dormancy.

I googled it and it seems they root pretty easily. Taken from Midwest Gardening site: " Dappled willow can be propagated from softwood or semi-hardwood cuttings. To produce new plants, just plant 8” cuttings of stem without leaves into consistently moist soil in a small pot or nursery bed, they will generally root easily. " I do a lot of cuttings. I use pro mix and perlite mostly. Since cuttings have no roots, you want the medium to be moist but not wet. It doesn't have to be promix used, either. You just don't want anything with fertilizer.

A lot depends on what you mean by 'invasive'. All willows (Salix spp.) have aggressive roots, tree forms much more so than the shrub forms. Tree willows can grow to a very large size (60'+) and tend to have very aggressive, water seeking roots. They will invade any nearby water source (inground plumbing, water pipes/mains, irrigation systems, septic fields, etc. They are NOT recommended for a typical suburban garden. In general, shrub willows do not have aggressive root systems and will not invade or aggressively seek out water sources. However, if they have been grafted and sold as a tree form, the grafted rootstock may very well have a more aggressively spreading root system than just the straight shrub. Keep in mind that the grafted form of dappled willow is intended for use in the average garden so unlikely to have the same overly aggressive, invasive behavior as would a weeping willow, for example. How close will the hedge be in relation to the French drain?