Abstract
Observations of flower buds of Dendrobium Tomie `Tokyo,' D Indonesia, and seedlings of a Dendrobium hybrid flowering for the first 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. Our results indicate that (1) only buds, flowers in the process of opening, and newly opened blossoms can undergo resupination; (2) mature flowers cannot reorient themselves if the angle of the inflorescence is changed; and (3) bending and twisting of the pedicel contribute to the final position of the flower.
Highlights
Resupination was defined by LEE as" . . . when the upper Lip of the Corolla looks toward the Ground, and the under Lip toward Heaven." JOHN LINDLEY (1853; cited in AMES [ 1938]) described orchid flowers as being resupinate
In Tricho pilia suavis the flowers are oriented with the lip lowermost by a slight torsion of the pedicel rather than the ovary (AMES 1947)
Resupination functions to place the labellum in a position that facilitates pollination (AMES 1948)
Summary
OPENING AND RESUPINATION IN BUDS AND FLOWERS OF DENDROBIUM (ORCHIDACEAE) HYBRIDS 1. Observations of flower buds of Dendrobi1w1 Tomie 'Tokyo.· D. Seedlings of a Dendrobiwn hybrid flowering for the first time showed that all flower buds were borne with the labellum uppermost. 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. Flowers in the process of opening, and newly opened blossoms can undergo rcsupination; (2) mature flowers cannot reorient themselves if the angle of the inflorescence is changed: and (3 ) bending and twisting of the pedicel contribute to the final position of the flower Our results indicate that (1 ) only buds. flowers in the process of opening, and newly opened blossoms can undergo rcsupination; (2) mature flowers cannot reorient themselves if the angle of the inflorescence is changed: and (3 ) bending and twisting of the pedicel contribute to the final position of the flower
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