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Why do conifers rely mainly on tracheids for both support and water transport?

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temperate softwoods and hardwoods selected to show variations — wood Temperate softwoods (left column) and hardwoods (right column), selected to highlight natural variations in colour and figure: (A) Douglas fir, (B) sugar pine, (C) redwood, (D) white oak, (E) American sycamore, and (F) black cherry. Each image shows (from left to right) transverse, radial, and tangential surfaces. Click on an individual image for an enlarged view.

In conifers, tracheids are the primary components of the xylem because they are the only vascular tissue elements present that serve both mechanical support and water conduction functions.12

Unlike angiosperms, which evolved a more specialized system separating these roles into vessels for conduction and fibers for strength, conifers rely on the structural properties of the tracheid itself. These cells are elongated, spindle-shaped, and reinforced by lignified secondary walls, which provide the necessary physical rigidity to support the tree's height.3415

For water transport, tracheids function by moving fluids through pits in their cell walls. While this system is less efficient than the vessel-based transport found in flowering plants, it is highly reliable; the small size of the conducting units and the presence of pit membranes help prevent the spread of air bubbles (embolisms) that could otherwise disrupt water flow, offering a degree of safety against injury.143