UC Irvine

Observations of flower buds of Dendrobium Tomie ’Tokyo’, Dendrobium ’Indonesia’, and seedlings of a Dendrobium hybrid flowering for the 1st time showed that all flower buds were borne with the labellum uppermost. Just before or during opening, the buds turned, positioning the lip below all other floral segments in a process known as resupination. The degree of turning depended on the orientation of the inflorescence relative to the ground and position of the pedicel. Individual flowers, at successive nodes along the inflorescence, alternated in turning clockwise and counterclockwise. Only buds, flowers in the process of opening, and newly opened blossoms can undergo resupination. Mature flowers cannot reorient themselves if the angle of the inflorescence is changed, and bending and twisting of the pedicel contribute to the final position of the flower.