To better understand the functions of coniifers and pinecones, micro-CT is increasingly used to analyze their internal structure and to efficiently monitor the morphology of pinecones as they are altered by their external environment. Micro-CT is used with pinecones for tree breeding studies to confirm when pollination and fertilization occurred and to assess seed viability. Pinecones in particular are studied due to the flexible nature of their outer scale movement with changes in humidity. Scientists also investigate pinecone fossils for documented evidence of water-driven opening and closing motions in coalified conifer cones, study conifer tree rings for climatological purposes, explore soft-rot decayed conifer wood in 3D, and more.
Hygroscopic motions of fossil conifer cones
Conifer cones represent natural, woody structures that open and close their scales as passive responses to changes in humidity. This study looks at water-driven opening and closing in “coalified conifer cones from the Eemian Interglacial (approx. 126,000–113,000 years BP) and from the Middle Miocene (approx. 16.5 to 11.5 million years BP). These cones represent by far the oldest documented evidence of plant parts showing full functionality of such passive hydraulically actuated motion”. The functionality is more than the biological purpose of seed dispersal and protection and is due to a low level of mineralization of the fossils. “Our analysis emphasizes the functional-morphological integrity of these biological compliant mechanisms which, in addition to their biological fascination, are potentially also role models for resilient and maintenance-free biomimetic applications (e.g., adaptive and autonomously moving structures including passive hydraulic actuators)”.
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Functional Principles of Morphological and Anatomical Structures in Pinecones
This study analyzed the anatomical and morphological features of internal and external pinecones to investigate comprehensive structural characteristics that may help develop ways of delivering new technology from their hygroscopic functions. Researchers measured the opening and closing angles of cone scales using micro-CT. Additionally, they investigated the pores on the surface of cone scales to better understand moisture absorption and dehumidification in pinecones to indirectly determine water absorption ability.
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Three-Dimensional Exploration of Soft-Rot Decayed Conifer and Angiosperm Wood by X-Ray Micro-Computed Tomography
The decomposed structure of conifer and angiosperm wood after colonization by soft rot fungi was investigated by the use of micro-CT in this study. There were challenges in visualization because of a decreased grayscale contrast, or X-ray density, of the degraded wood but the researchers were able to image “fungal-induced cell deformations in earlywood and cavities in the thick wall of latewood cells” in 3D. Unlike the organic wood material, the higher X-ray density of inorganic deposits was easier to image.
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X-ray imaging and computed tomography of conifer tree rings for climatological purposes
Tree rings are a known indicator of climatic changes, utilizing the number and width of tree rings; structure (pattern); and wood density as the main dendrometric characteristics. “The research aimed to develop a technique to assess the structure and density of tree rings of trunk wood using a high resolution scanning X-ray tomograph to solve dendroclimatology and biometeorology related problems”. The study demonstrated that micro-CT is valuable for the investigation of wood fine structure and precise measurement of the width and density of tree rings without destroying the wood samples.
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