I have previously written about two fine old primary hybrids made with Paphiopedilum rothschildianum: the Victorian P. Lady Isobel and P. Saint Swithin. Here is a modern one, and it may well be the best.
Paphiopedilum Johanna Burkhardt is P. rothschildianum x P. adductum, and it was registered in 1994. My plant was made using P. adductum var. anitum as the pollen parent, and the results are spectacular. P. rothschildianum has contributed flower size, number, and overall form, while genes from the very dark P. adductum var. anitum have produced a dorsal sepal, petals, and pouch with dark reddish-brown markings on a yellow background. P. adductum var. anitum has also reduced the overall size of the plant, without affecting flower size; this plant has about half the leaf-span of my other P. rothschildianum hybrids, but its flowers are just as large, if not larger. A Google search for this grex will turn up pictures of better clones, many of them awarded, with huge, muscular-looking flowers and dorsal sepals that are almost black.
P. adductum var. anitum is sometimes considered a separate species, P. anitum, in which case this hybrid would be P. Wössner Black Wings (P. rothschildianum x P. anitum). From a horticultural point of view, there’s something to be said for distinguishing the dark plants made with P. adductum var anitum from those made with lighter colored P. adductum clones. However, the International Orchid Register lists P. Wössner Black Wings as a later synonym of P. Johanna Burkhardt, and both the Kew World Checklist of Selected Plant Families and a recent checklist of the genus Paphiopedilum (Koopowitz, H., 2018, Orchid Digest 82: 178-235) consider P. anitum to be a synonym of P. adductum.
Eight hybrids using P. Johanna Burkhardt as a parent have been registered, but none of the photos I have seen suggest that they are any better than–or even as good as–their parent. I’d go so far as to say that in this group of orchids, the primary hybrids are almost always better than complex hybrids. After more than 120 years, P. Lady Isobel and P. Saint Swithin are still well worth growing, and I suspect that the same will be true of P. Johanna Burkhardt in another century.