Quantitative Examination of the Anatomy of the Juvenile Sugar Maple Xylem

October 13, 2023

Our team have recently published a journal paper characterising the anatomy of the xylem in juvenile sugar maple trees.

T.Driller, J.A. Robinson, M. Clearwater, D.J. Holland, A. van den Berg, M.Watson. 2023. Quantitative Examination of the Anatomy of the Juvenile Sugar Maple Xylem. PLOS ONE.

Maple trees have a particular stem structure, specifically the xylem tissue. This water-conducting (vascular) tissue of plants is responsible for the upward conduction of water and nutrients from the roots, and is where elevated stem pressures develop during freeze-thaw events. This is important, because the elevated stem pressure is what enables the collection of maple sap in the springtime—a tree is wounded (cut or drilled) and the sap exudes from the tree due to the high stem pressure. Syrup producers often apply vacuum to further improve sap yields.

The exact mechanisms involved in this process are yet to be fully resolved. Pressure is believed to develop due to processes occurring within individual cells of the xylem.

We have used light optical microscopy (LOM) and scanning electron microscopy (SEM) to study these microstructures in juvenile sugar maple stems. Information on the size, distribution and cell wall structure of each xylem element is being used to improve understanding of the tree stem’s hydraulic conductivity, patterns of sap flow, cell wall composition, and the other important factors involved in maple sap exudation, such as water conduction, and capillary and osmotic forces.

Macerated xylem cells observed using SEM. Lines used to measure the cell lengths are shown in pink. The yellow circle indicated a fibre which was broken and not measured. The scale bar is 100 μm.
LOM image of transverse xylem slice showing fibres. Black arrows point to intercellular spaces while red arrow points to radial files of larger fibres (scale is 25 μm).

The results obtained were in general agreement with the few existing findings on mature sugar maple xylem, with some differences in the measured fibre and vessel element lengths.

There is scope for future work to investigate methods for distinguishing between different fibre types, and further exploring the connections between fibres and other cell types.

Access the paper here.

Plant Physiology