Q Some people have said the flower produced by keikis on dendrobiums are of lower quality, which includes smaller flower size, shorter flower stem, and also weaker cut flowers than the flowers produced by the mother plant. Others say there is no difference between the flowers produced by keikis and mother plant. Which is correct? At what age does a dendrobium plant's flower production capacity start to decline?

A  In a sympodial orchid like hardcane Dendrobium I would say there would be no difference between the productivity of the originating plant and the keiki. Much orchid folklore has little basis in fact but you can always prove this for yourself over a period of several years. Select 25 plants with keikis and record the flower production of the older plants over a 12-month period. Then grow the keikis up to the same plant and pot size and record their productivity over a similar 12-month period starting and ending in the same months as the originals. This is not strictly a controlled experiment but it should allay any concerns you might have.

As a sympodial orchid, a hardcane Dendrobium plant should show no decline in productivity over its life. But, in practice, this seems to be only partially true. What is possibly occurring is that some systemic diseases, viruses and bacteria are making their presence felt. It is also possible that some genetic change occurs in the plants. The late Don Wimber, PhD, believed that, in the Odontoglossum Alliance (which is notoriously unstable), a chromosome change actually was occurring in some hybrids in cultivation. This would seem to go against all we know in science — yet strange things happen in orchids. Few people imagined that phalaenopsis would be CAM (Crassulacean Acid Metabolism) Cycle plants and this discovery has had a major influence on their culture. Much more will be known when the results of currently funded AOS research are complete, probably by early in 2004, but it is important to remember that CAM-cycle plants have their stomata open at night and this is when they are taking in carbon dioxide most efficiently for later use in photosynthesis.

As researchers study orchids more intensively I think our knowledge base will alter quite dramatically.   —Andy Easton.