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Abgeschickt von Darcy Gunnlaugson am 29 Maerz, 2000 um 06:04:40
I thought I should post the following tentative clarification for the reason of color instability reported in C. reginae alba clones.... as confusion over it continues to be posed from European quarters.
There is an unstable form of white C. reginae which occassionaly fails to complete the biochemical pathway that allows for the pink coloration. It is an aberrant, and under normal conditions, it is a normally colored form, but it is believed the enzyme necessary to complete the color conversion is somehow "turned off" (using the analogy of a switch) by temperatures higher than some threshold. When this temperature trigger occurs, this form will bloom white.. but still have pale pink striations visible, even though the pink color isn't activated. The full alba form (albolabium) by contrast (photo), has only yellow striations visible in the otherwise pure white flower. So, two white forms do exist, and one is an unstable form which will, depending on spring temperatures, exibit itself as a white form , or alternately in a normal spring, as a normally colored form. Also, unlike the albolabium form, which is "reported" sterile, this form produces bountiful seed which grow to be normal appearing reginae.
Of this unstable abberant form John Doherty wrote in the North American Native Orchid Alliance Journal in March of 1997, where he indicated that "pigmentation may be partially due to the ambient during floral developement". He indicated (in his issue long treatment of the genus) that this temperature factor can influence this particular clone to display alba characteristics if an early heat wave occurs while the flower is in bud. Such a plant will then bloom similar to a pure alba for that season, but revert to it's normal color form if the subsequent spring has normal temperatures.
I hope this is of some assistance to those of you still puzzled by this phenomena or wondering if a true albolabium exists (and it does).
DarcyPS: Acknowledgments to John Dogherty and Richard on The Mountain in Gatlinburg