I found it strange that people were jumping in to question R.E. Holttum's botany and knowledge of orchids. After all, this is the man who was the director of the Singapore Botanic Gardens from 1925 to 1949, and was then Professor of Botany at the University of Singapore until his 1954, and was awarded an Sc.D. degree by Cambridge University in 1951 in recognition of his published works on Malaysian botany. With his experience, Holttum is unlikely to have been ignorant of the fact that Vanda roots are often completely aerial.
So I read the article (thanks to Stephen Manza for providing the link), and it was immediately obvious that those who criticized Holttum's expertise simply hadn't bothered checking before blasting .... but then, we've come to expect that, haven't we ? Holttum wasn't describing his own findings .... he was quoting a couple of other researchers ... Dycus & Knudson (Bot. Gaz. 119, 78-87, 1957). So Andy, it looks like you're going to have to revise your statements to read: "Knudson was no physiologist", and "Knudson had little practical knowledge of orchid culture." Please don't forget to post your corrections here on OGD, Andy ... we're all looking forward to reading them. BTW Stephen, although Holttum's quotation says that little of the water absorbed by the velamen is passed to the interior of the root, it DOESN'T say "absorption of water and nutrients is limited to the areas of the roots growing in contact with the substrate." Perhaps that came from some other source ? Cheers, Peter O'Byrne in Singapore _______________________________________________ the OrchidGuide Digest (OGD) orchids@orchidguide.com http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
