Loss of leaf surface wax during winter could contribute to the extreme desiccation and leaf mortality previously observed for timberline conifers. For Picea engelmannii, leaf surface wax declined most rapidly for leaves above the snowpack as winter progressed, until there was approximately 60% less surface wax than for leaves protected by snow cover. Near the upper limit of the timberline ecotone (3400 m), leaves of P. engelmannii had less surface wax compared to individuals near the lower ecotone limit (3200 m), as well as smaller differences between windward versus leeward sides of the same shoot. Abies lasiocarpa leaves at 3400 m had the least amount of wax, while leaves of Pinus contorta at a lower, wind-exposed site (3100 m) had the greatest amount. Only small differences in wax quantities occurred on windward versus leeward leaves on P. contorta saplings, despite much higher mortality for windward leaves near the snow surface. From measurements on artificial wax cylinders placed in the field, an inc...