MORPHOLOGY AND DISTRIBUTION OF PETIOLAR NECTARIES IN IPOMOEA (CONVOLVULACEAE) |
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Authors: | Kathleen H. Keeler Robert B. Kaul |
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Affiliation: | School of Life Sciences, University of Nebraska, Lincoln, Nebraska, 68588 |
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Abstract: | The distribution of petiolar nectaries in 24 species of Ipomoea was investigated. Petiolar nectaries were found on 12 species (8 new reports, 4 confirmations of previous reports) and quoted from the literature as being found on 3 other species; they were absent from 9 species investigated. The structure of petiolar nectaries in the genus ranges from simple beds of superficial nectar-secreting trichomes (1 species), to slightly recessed “basin nectaries” (8 species), to “crypt nectaries,” which are structurally the most complex extrafloral nectaries known (3 species). (Structures were not determined for 3 species.) Petiolar nectaries are present in all subgenera, but all crypt nectaries occur in the same section (Eriospermum). Species with extrafloral nectaries tend to be perennial; species lacking extrafloral nectaries tend to be annual. There is no relationship between temperate or tropical habitat and presence of nectaries. |
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