why gymnosperms lack vessels in their xylem?

Gymnosperms are seed bearing, non flowering plants, Vascular bundles are present but xylem lacks vessels and phloem lacks companion cells. Vessels element is mainly found in xylem and is typically found in flowering plants (angiosperm) and are absent in softwood plants such as conifers (gymnosperm) as these plants do not produce flowers. Because the flowering plants requires more supply of water for their growth, these vessel elements plays major role there as these elements form an efficient  system for transporting water from the roots to the leaves and then other parts of the plants.