Conifer ovulate cones accumulate pollen principally by simple impaction

Cresswell, James; Henning, Kevin S. S.; Pennel, Christophe; Lahoubi, M.; Michael, Patrick; Young, Phillipe G.; Tabor, Gavin

doi:10.1073/pnas.0706434104

Cited by 18 publications

(14 citation statements)

References 26 publications

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“…To our knowledge this is the first time that computerized axial tomography is used for this type of evaluation in pine cones, although this technique has been applied at other related research areas e.g. in conifer seeds and cones (Cresswell et al, 2007;Gee, 2013), wood and fibers (Bensadoun et al, 2014) and cork (Oliveira et al, 2015).…”

Section: Resultsmentioning

confidence: 99%

Short communication. Tomography as a method to study umbrella pine (Pinus pinea) cones and nuts

et al. 2016

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Aim of study: Umbrella or stone pine (Pinus pinea) nuts are one of the most valuable and expensive non-wood forest products in Portugal. The increasing market and landowner's interest resulted on a high expansion of plantation areas. This study tests the feasibility of using tomography to characterize pine cones and nuts.Area of study: The research was carried out in pine stand, with nine years, grafted in 2011, on Herdade of Machoqueira do Grou, near Coruche, in Portugal's central area.Material and methods: Starting in June 2015, ten pine cones in their final stage of development, were randomly monthly collected, and evaluated with tomography equipment commonly used in clinical medicine, according to Protocol Abdomen Mean. A sequence of images corresponding to 1mm-spaced cross-sections were obtained and reconstructed to produce a 3D model. The segmented images were worked using free image processing software, like RadiAnt Dicom Viewer, Data Viewer and Ctvox.Main results: The cone's structures were clearly visible on the images, and it was possible to easily identify empty pine nuts. Although expensive, tomography is an easy and quick application technique that allows to assess the internal structures, through the contrast of materials densities, allowing to estimate pine nut's size and empty nut's proportion. By analysis of ninety images, it was obtained, an estimated mean value of 25.5 % empty nuts.Research highlights: Results showed the potential of tomography as a screening tool to be used in industry and research areas, for analysis and diagnostic of stone pine cone's structures.

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Section: Resultsmentioning

confidence: 99%

Short communication. Tomography as a method to study umbrella pine (Pinus pinea) cones and nuts

et al. 2016

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“…The wind tunnel had a cross‐section of 120 × 120 mm over a horizontal run of 600 mm with an aerodynamically shaped contraction beginning with an initial cross‐section of 250 × 250 mm, which was identical in all respects except scale to the tunnel pictured in Cresswell et al. (2007).…”

Section: Methodsmentioning

confidence: 99%

“…Pollen was loaded into a narrow nozzle formed from a trimmed 200 μL pipette tip (Life Sciences International, Basingstoke, UK) and injected into the contraction of the wind tunnel by a single puff from an attached syringe. To produce a uniform cloud, pollen was dispersed during injection with a baffle (8 × 8 mm mounted 25 mm in front of the nozzle) placed 60 mm from the tunnel’s contraction (Cresswell et al. 2007).…”

Section: Methodsmentioning

confidence: 99%

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The aerodynamics and efficiency of wind pollination in grasses

et al. 2010

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Summary1. Under natural selection for sexual success, the reproductive organs of plants should evolve to become highly effective pollen receptors. Among wind-pollinated plants, larger reproductive structures appear counter-adapted to accumulate pollen by impaction on their windward surfaces, because airborne particles are less able to penetrate the thicker boundary layer of larger targets. Therefore, it has been proposed that wind-pollinated plants with pollen receptors on relatively large structures, like some grasses (family Poaceae), are architecturally adapted to create downstream vortices in which airborne pollen recirculates before accumulating on leeward surfaces. From this basis, the striking diversity among the grasses in the architecture of their flowering stems has been attributed in part to the existence of these contrasting mechanisms for effecting pollen receipt, namely impact collection and recirculatory collection. 2. We investigated the relative importance of impact and recirculatory collection in grasses by analysing a model system in silico using Computational Fluid Dynamics and by conducting in vivo experiments, both in a wind tunnel and outdoors, using two grass species with compact inflorescences, Alopecurus pratensis and Anthoxanthum odoratum. 3. Irrespective of the experimental approach, we found that although pollen recirculated in the leeward eddies of inflorescences, over 95% of the accumulated pollen was collected by windward surfaces. 4. In A. pratensis, the collection efficiency (proportion of oncoming pollen collected) was between 5% and 20%, depending on wind speed in the range 0AE5-1AE9 m s )1 and these levels conform to those predicted by a mechanistic model of impact collection.5. Our results demonstrate that grass species with larger inflorescences are, like those with smaller inflorescences, primarily impact collectors of airborne pollen, which suggests that dissimilar reproductive morphology among species cannot be attributed to differentiation in the mode of pollen capture and, instead, requires reference to other factors, such as the need to produce, protect and disperse seeds of different sizes in different environments.

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“…Conifers produce pollen in vast quantities: the pollen settles out of the air slowly, perhaps aided by aerodynamic features of pollen microstructure such as air sacs; the cones are presented on aerodynamically exposed branch tips to minimize pollen filtering by foliage; like most wind-pollinated plants they tend to grow in high-density monospecific stands; and the cone architecture may be adapted to physically intercept and direct pollen-bearing air currents to increase the effectiveness of wind pollination (Niklas & Kyaw, 1982;Whitehead, 1983;Niklas, 1985;Owens, Takaso & Runions, 1998;Di-Giovanni & Kevan, 1991;Di-Giovanni, Kevan & Nasr, 1995;Roussy & Kevan, 2000;Cresswell et al, 2007;Schwendemann et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Does pollen aerodynamics correlate with pollination vector? Pollen settling velocity as a test for wind versus insect pollination among cycads (Gymnospermae: Cycadaceae: Zamiaceae)

Hall

Walter

2011

Biological Journal of the Linnean Society

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Studies of cycad pollination globally have revealed obligate pollination mutualisms with insects, typically hostspecific beetles. Some cycads in the genus Cycas have floating seeds allowing oceanic dispersal, and have colonized remote islands such as Fiji, Guam, and Madagascar. This seems to contradict the expected requirement that specific beetle pollinators be present in order for cycads to establish in remote localities. We therefore postulated that these 'island' cycads are wind pollinated. We tested for adaptations associated with wind pollination in a laboratory study of pollen aerodynamics. The pollen from a range of (non-cycad) wind-pollinated plants was not relatively 'buoyant': the settling velocities of wind-pollinated species exceeded those of insect-pollinated cycads and some animal-pollinated angiosperms. We attributed this result to settling velocity being, in part, correlated with pollen size, as cycad pollen was consistently smaller. A better predictor for pollination vector was the tendency of pollen to aggregate during a vertical fall. Pollen of wind-pollinated plants separated into single grains, whereas cycad pollen and pollen of animal-pollinated angiosperms adhered in large aggregations, the settling velocity of which increased rapidly with aggregate size. The pollen of cycads known to be insect pollinated was similar in morphology, settling speed, and clumping behaviour to pollen of 'island' cycads of unknown pollination biology. Based on these aerodynamics, we predict that cycad species on oceanic islands have insect pollinators. More broadly, we propose that pollen aggregation during a vertical fall provides a sound test for wind versus animal pollination when the pollination vector is unknown.

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Conifer ovulate cones accumulate pollen principally by simple impaction

Cited by 18 publications

References 26 publications

Short communication. Tomography as a method to study umbrella pine (Pinus pinea) cones and nuts

Short communication. Tomography as a method to study umbrella pine (Pinus pinea) cones and nuts

The aerodynamics and efficiency of wind pollination in grasses

Does pollen aerodynamics correlate with pollination vector? Pollen settling velocity as a test for wind versus insect pollination among cycads (Gymnospermae: Cycadaceae: Zamiaceae)

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