Japanese maple seedlings used for grafting can have either color bark but they are all the same plant, Acer Palmatum. It will have no impact on the health of the tree just the cosmetics. Grafters should try to match the color of the bark on the seedling with the color of the bark of the cultivar being grafted for the best looking tree. Since your plant are weeping eventually the seeding that the plant was grafted onto won't be very noticable. David

I will mention that you would be very hard pressed to find a weeping laceleaf seedling (or any japanese maple other than a green upright or red upright) About 95 percent of all laceleafs are grafted and probably less than one out of a thousand are seedlings these days. Note that you might find one at a small time back yard grower or something, but you wouldn't likely find one at a typical nursery.

re: I will mention that you would be very hard pressed to find a weeping laceleaf seedling

true but you might find one if you grow enough seed. I grew several hundred last year and found 2 dissected type seedlings from a batch of generic autropurpureum seed. Also found a reticulated type and, from a batch of generic green seed a variegated plant that produces some all white leaves, some all green leaves and some split right down the middle.

Ill post some pictures when they leaf out.

Yes you are probably more likely to find one in a batch of your own seedlings than for sale. I think most growers horde the unusual ones just in case it is the next great dissectum (or other unusual variety for that matter).