Dioecy and Pollination of Morinda umbellata subsp. umbellata (Rubiaceae) in the Ryukyu Islands Dioecy and Pollination of Morinda umbellata subsp. umbellata (Rubiaceae) in the Ryukyu Islands

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Abstract

Sex expression and pollination were examined in natural populations of Morinda umbellata subsp. umbellata (Rubiaceae), a woody climber distributed widely in southeastern Asia, including southwestern Japan. Sex expression of subsp. umbellata was confirmed as being functionally dioecious, with separate staminate and pistillate plants. Staminate flowers had four or five stamens and completely lacked a style and stigma, while pistillate flowers had a style with two stigmatic lobes and four or five abortive stamens, the anthers of which produced no functional pollen grains. The stigmas of pistillate flowers protrude beyond the corolla tube and are positioned above the anthers, whereas anthers of the staminate flowers protrude beyond the corolla tube, indicating that stigma and anther heights appear to be reciprocal between pistillate and staminate flowers. Both flowers produced nectar from the base of the corolla tube, and the nectar volume per flower did not differ significantly between the two sexual morphs. Various unspecialized, opportunistic insects, such as wasps, small bees, hover-flies, bee-flies, beetles, and butterflies, visited the flowers mainly to feed on nectar. Of these, small bees, wasps, hover-flies, and beetles appear to be effective pollinators of subsp. umbellata. The floral and reproductive characteristics of subsp. umbellata were compared with those of subsp. boninensis, which exhibits androdioecy.

Journal

  • Acta phytotaxonomica et geobotanica

    Acta phytotaxonomica et geobotanica 61(2), 65-74, 2010

    The Japanese Society for Plant Systematics

References:  26

Cited by:  1

Codes

  • NII Article ID (NAID)
    110009804242
  • NII NACSIS-CAT ID (NCID)
    AA11586265
  • Text Lang
    ENG
  • Article Type
    Journal Article
  • ISSN
    1346-7565
  • Data Source
    CJP  CJPref  NII-ELS  J-STAGE 
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