Flower orientation in Pachycereus pringlei
2000; Canadian Science Publishing; Volume: 78; Issue: 12 Linguagem: Inglês
10.1139/b00-133
ISSN1480-3305
AutoresClara Tinoco‐Ojanguren, Francisco Molina‐Freaner,
Tópico(s)Plant Diversity and Evolution
ResumoThe orientation of flowers in columnar cacti has been a subject of great interest to plant biologists. The interpretation of this pattern has invoked warmer temperatures as the underlying factor. In this paper, we describe flower orientation in two populations of Pachycereus pringlei (S. Watson) Britton & Rose and propose a hypothesis of the underlying mechanism. Stems from the two populations showed a significant mean direction of their flowers, with most flowers (70-77%) present between 90 and 270°. Photosynthetic photon flux density interception and stem temperature reached maximum values on south-facing ribs, showing concordance with flower orientation. We suggest that PFD interception, through its influence on CO 2 uptake and stem temperature, is the major factor underlying the observed orientation of flowers in P. pringlei.Key words: columnar cacti, flower orientation, Pachycereus pringlei, PFD interception.
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