Vascular systems are intimately related to the shape and spatial arrangement of the plant organs they support. We investigate the largely unexplored association between spiral phyllotaxis and the vascular system in Asteraceae flowers heads. We imaged heads of eight species using synchrotron-based X-ray micro-computed tomography and applied original virtual reality and haptic software to explore head vasculature in three dimensions. We then constructed a computational model to infer a plausible patterning mechanism. The vascular system in the head of the model plant Gerbera hybrida is qualitatively different from those of Bellis perennis and Helianthus annuus, characterized previously. Cirsium vulgare, Craspedia globosa, Echinacea purpurea, Echinops bannaticus, and Tanacetum vulgare represent variants of the Bellis and Helianthus systems. In each species the layout of the main strands is stereotypical, but details vary. The observed vascular patterns can be generated by a common computational model with different parameter values. In spite of the observed differences of vascular systems in heads, they may be produced by a conserved mechanism. The diversity and irregularities of vasculature stand in contrast with the relative uniformity and regularity of phyllotactic patterns, confirming that phyllotaxis in heads is not driven by the vasculature.
Download the paper from the publisher's site or from here.
Download the supporting information from the publisher's site or from here.
Download the supporting model description from the publisher's site or from here.
Download the preprint from bioRxiv.
Download Movie 1 here -- Fly-through of a scanned and segmented gerbera head. (MP4, 26.4 MB)
Download Movie 2 here -- Simulated development of a Bellis head vasculature - side view. (MP4, 3.5 MB)
Download Movie 3 here -- Simulated development of a Bellis head vasculature - top view. (MP4, 4.2 MB)
Download Movie 4 here -- Simulated development of a sunflower head vasculature - side view. (MP4, 1.7 MB)
Download Movie 5 here -- Simulated development of a sunflower head vasculature - high-angle view. (MP4, 5.5 MB)
Download Movie 6 here -- Simulated development of a sunflower head vasculature - top view. (MP4, 6.1 MB)
Download Movie 7 here -- Simulated development of a gerbera head vasculature - side view. (MP4, 2.7 MB)
Download Movie 8 here -- Simulated development of a gerbera head vasculature - high-angle view. (MP4, 9.7 MB)
Download Movie 9 here -- Simulated development of a gerbera head vasculature - top view. (MP4, 8.7 MB)
Download the reconstructed image stacks, segmentation masks, and polygon meshes from BioImage Archive.
Download a smaller set of down-sampled data for the eight species in our study from the X-plant site.
Download our software, SHVR and ViNE, to visualize and segment the images stacks and meshes.
The source code respositories for SHVR and for ViNE are available on GitHub.
Download the gerbera phyllotaxis model here (TGZ archive, 15.7 MB)
Download the gerbera vasculature model here (TGZ archive, 158.6 MB)
Download the sunflower phyllotaxis model here (TGZ archive, 25.2 MB)
Download the sunflower vasculature model here (TGZ archive, 76.1 MB)
Download the bellis phyllotaxis model here (TGZ archive, 25.5 MB)
Download the bellis vasculature model here (TGZ archive, 54.8 MB)
The models may also be cloned from our repository on GitHub.
You will need VLAB to run the models. They were tested using VLAB verison 5.0 on macOS 10.13 (High Sierra).