Hi Greg, I have no difficulty with anything in the article you wrote, reference:
http://www.geocities.com/pennypoint9/dendrob.html Most of the stuff is well covered in the literature. The photos at the bottom are clear and detailed, and portray the forms of D. bigibbum and D. phalaenopsis that would be most familiar to growers. If you only look at these forms, you see two clear-cut species. My difficulties lie with what you haven't said in your article ... what you get when you look at the range of specimens. Your article mentions Dockrill's D. bigibbum var. compactum, but it's contribution to D. bigibbum has been omitted from your table. This variety has a lip shape almost identical to D. phalaenopsis, but only about half the size. If you add the characters of D. bigibbum var. compactum to your table, no significant difference remains between the taxa. Some authors have resolved this difficulty by listing var. compactum as "D. phalaenopsis var. compactum", but by doing this one of the specific characters for D. phalaenopsis (it's larger flower size) is lost; only the different lip shape remains. This is insufficient to maintain it as a distinct species to D. bigibbum; you need 2 consistently different characters, not one. There is a further problem; the New Guinea form of D. bigibbum (see my Lowland Orchids of PNG, page 232) has flowers 56 mm wide, acuminate petals and lateral sepals (as in your D. phalaenopsis), a lip with the keels and sidelobe shape of your D. bigibbum, but a midlobe with parallel lateral margins (as in your D. phalaenopsis) and a truncate front margin with a small apical point. This form really muddies the waters; try adding this to the table and see what you end up with ! Some authors have tried to settle this problem by stating that there are 3 different species. Following this logic, the New Guinea plants would have to be a 4th species. This approach is unsatisfactory because you cannot get 2 consistently different characters between each pair of taxa, so the authors tend to get round this problem by counting the same difference twice, eg "D. compactum differs from D. phalaenopsis by having (1) much smaller flowers, and (2) much smaller stems". Sorry, I don't swallow this. If D. compactum is a miniature form of D. phalaenopsis (or D. bigibbum), then it would be "smaller than" in all its parts ... that is one difference, not two. Cheers, Peter O'Byrne Singapore _______________________________________________ the OrchidGuide Digest (OGD) [EMAIL PROTECTED] http://lists.orchidguide.com/mailman/listinfo/orchids
