I appreciate Rick pointing out that he had referred to seedlings in his
remarks about prismatica, versicolor, and setosa and that my comment may
not have been applicable in that case. Apart from height, however, I
think that the distinguishing features that I mentioned as separating
these species are equally applicable to the pre-flowering seedlings.
The purple base of the leaves, for example, is found on seedlings that
are certainly less than a foot high.
Ian in Ottawa, where there is still no sign of a frost which can come
anytime after the beginning of September in some years.