The mirror crack'd: Both pigment and structure contribute to the glossy blue appearance of the mirror orchid, Ophrys speculum

Silvia Vignolini, Matthew P. Davey, Richard M. Bateman, Paula J. Rudall, Edwige Moyroud, Julia Tratt, Svante Malmgren, Ullrich Steiner, Beverley J. Glover

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

The Mediterranean orchid genus Ophrys is remarkable for its pseudocopulatory pollination mechanism; naïve male pollinators are attracted to the flowers by olfactory, visual and tactile cues. The most striking visual cue is a highly reflective, blue speculum region at the centre of the labellum, which mimics the corresponding female insect and reaches its strongest development in the mirror orchid, O. speculum. We explored the structure and properties of the much-discussed speculum by scanning and transmission electron microscopic examination of its ultrastructure, visible and ultraviolet (UV) angle-resolved spectrophotometry of the intact tissue, and mass spectrometry of extracted pigments. The speculum contrasts with the surrounding labellar epidermis in being flat-celled with a thick, smooth cuticle. The speculum is extremely glossy, reflecting intense white light in a specular direction, but at more oblique angles it predominantly reflects blue and UV light. Pigments in the speculum, dominantly the cyanidin 3-(3′′-malonylglucoside), are less diverse than in the surrounding regions of the labellar epidermis and lack quercetin copigments. Several physical and biochemical processes interact to produce the striking and much-discussed optical effects in these flowers, but the blue colour is not produced by structural means and is not iridescent.

Original languageEnglish
Pages (from-to)1038-1047
Number of pages10
JournalNew Phytologist
Volume196
Issue number4
Early online date9 Oct 2012
DOIs
Publication statusPublished - 1 Dec 2012

Keywords

  • Anthocyanin
  • Copigmentation
  • Epidermis
  • Labellum
  • Ophrys speculum
  • Pollinator deceit
  • Specular reflection
  • Structural colour

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