Do pine needles retain water

Yes, as is the case with foliage in general, the needles of the pine tree [Pinus spp] retain water. The needles are thick skinned and wax coated to keep inside the dissolved nutrients that the tree receives from the roots. As is the case with foliage, needles have breathing pores called 'stomata' on their surfaces.

Breathing pores regulate the exchange of gases. Specifically, some moisture may be gained or lost in the form of water vapor. But the ways in which needles are shaped long and thin, and protected by thick skins and wax coatings, favor vital water retention by the tree.