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Backlund, A. & Nilsson, S.: Pollen morphology and the systematic position of Triplostegia (Dipsacales). - Taxon 46: 21-31. 1997. - ISSN 0040-0262.
Triplostegia comprises two species of perennial herbs from southeast Asia, T. glandulifera and T. grandiflora. The systematic position of the genus has been debated ever since it was described, and it has been placed in either Dipsacaceae or Valerianaceae, or in a family of its own Triplostegiaceae. Pollen of Triplostegia, investigated by light microscopy and scanning electron microscopy, is similar to that of both Dipsacaceae and Valerianaceae. Presence of numerous branched and bent columellae as well as an aperture margin structure resembling the halo found in Valerianaceae indicates a closer relationship to the Valerianaceae. A sister-group relationship between Triplostegia and the Valerianaceae is furthermore supported by other studies of molecular and morphological data. In order to maximize information content in the framework of mandatory classificational ranks, Triplostegia is best included in the family Valerianaceae, as the sole member of a subfamily Triplostegioideae.
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Effective publication date: 15 February 1997