Conifer ovulate cones accumulate pollen principally by simple impaction

Area of Science:

• Botany
• Aerodynamics
• Evolutionary Biology

Background:

• Pine ovulate cones (Family Pinaceae) often exhibit turbine-like structures.
• This morphology has been widely hypothesized as an adaptation for wind-mediated pollination through complex aerodynamic effects.

Purpose of the Study:

• To test the turbine hypothesis for pine ovulate cone function.
• To investigate the aerodynamic mechanisms of pollen accumulation on ovulate cones.

Main Methods:

• Quantified pollen accumulation on ovulate cones in a wind tunnel.
• Utilized computational fluid dynamics (CFD) simulation models.
• Created CFD models using computer-aided design and computed tomography for three species: Pinus radiata, Pinus sylvestris, and Cedrus libani.

Main Results:

• No significant contribution of turbine-like aerodynamics to pollen accumulation was found.
• Pollen accumulation occurred predominantly via simple impaction across all species and methods.
• The study found no evidence supporting the aerodynamic turbine hypothesis.

Conclusions:

• The turbine-like structure of pine ovulate cones may not be primarily for aerodynamic pollination enhancement.
• Alternative adaptive explanations for ovulate cone morphology are warranted.
• Findings challenge long-standing interpretations in plant reproductive biology.