The anatomy of bifurcations in trees requires further scientific investigation as the current anatomical model for them is logically flawed. The provision of a better model will assist in scientific studies of woody plants, the risk assessment of junctions in mature trees and provide bio-inspiration for Y-shaped joints in composite materials. In this study, the xylem formed in the central axis of a hazel (Corylus avellana L.) bifurcation is shown to provide a disproportionately greater amount of its tensile strength. CT scanning identified that this centrally-placed xylem was 28.1% denser, with 63% less vessels formed in this tissue, such vessels being 50.5% of the diameter and 32.5% of the length of those formed in adjacent stem tissues. The wood grain pattern at the bifurcation apices were 22 times more tortuous, forming interlocking patterns that acted to resist tensile forces by requiring the extraction or breaking of wood fibres along their length (the axial tensile strength of wood). Subsequent tests confirmed that this conferred more than 100% additional tensile strength to these specialised xylem tissues. These findings provided the basis of a novel anatomical model for bifurcations in woody plants. Further to this, the effects of several factors upon junction strength and biomechanical behaviour were assessed in bifurcations of hazel, identifying the weakening effect of bark inclusions and three types of artificial modification as well as differences in wind-induced movement between bifurcation types. This study concludes that further investigations of bifurcations in a wider range of woody plants and observations of the developmental stages of the interlocking wood grain patterns found at bifurcations would usefully add to existing knowledge.

The flow of blood in the human body is a very important component in un-derstanding a number of different ailments such as atherosclerosis and a falseaneurysm. In this thesis, we have utilized Poiseuille’s solution to Navier-Stokesequations with a Newtonian, incompressible fluid flowing laminar with zero ac-celeration in a pipe with non-flexible walls in order to study blood flow in anarterial tree. In order to study and simulate a larger arterial tree we have uti-lized a primitive building block, a bifurcation with one inlet and two outlets,joined together forming a tree. By prescribing an inlet flow and the pressureat every outlet at the bottom of the tree we have shown that we may solvethe system by fixed-point iteration, the Matlab functionfsolve, and Newton’smethod. This way of using primitive building blocks offers a flexible way to doanalysis as it makes it possible to easily change the shape of the tree as well asadding new building blocks such as a block that represents arteriosclerosis.