Capillary action is subject to the same limits as suction at the top. Capillary action can't increase the water pressure at the bottom of the tree.

If you put a straight thin capillary tube upright in water so it sucks up water from the bottom, no matter how thin, it can't draw water up above ~10m of water level.

Oh, so we don't really know how it works. Fun.

the research is relevant to the issue of transpiration column hieght as a postulated limitation to overall hieght of any tree.

a column of water is pulled by hydrogen bonding between molecules in a tug of war fashion, the top of the column is where water is dissociated from the column at such a rate as to maintain low pressure with respect to the column[xylem]

in summary water moves from bottom to top in a transpiration stream, that ultimately ejects water vapour from the leaves, resulting in a low efficiency mechanism, that loses a lot of the water but occurs at such a rate that the low efficiency is "good enough" for whats needed.

Capillary action and mechanical pumping by wind.