I was curious about that statement, Geoff, so I looked online. According to Michigan State University ( http://www.hrt.msu.edu/faculty/Runkl...sis_Part_2.pdf ) the following is the case:
"Phalaenopsis roots that are ex-posed to light have chloroplasts and perform photosynthesis. A majority of phalaenopsis growers in Taiwan and the Netherlands, and increasingly growers in the United States, use clear pots that allow light to penetrate the pots. Root photosynthesis likely contributes little to total plant photosynthesis. However, because phalaenopsis roots avoid darkness, roots of plants grown in clear pots generally stay inside the pot better than the roots of plants grown in opaque pots."
Perhaps orchids, being epiphytes, have abnormal roots? I'm not the expert, I have heard from many I consider experts that Phals can photosynthesize in their roots. I consider you an expert too though.