Vine Arrows
From The DarkMod Wiki
Vine arrows are available in TDM 1.07 and later.
They spawn a climbable vine on many rough surfaces.
Surfaces more than 60 degrees off vertical will not accept an arrow (i.e. ceilings and floors).
If the surface doesn't accept the vine arrow, the arrow will bounce off and you can retrieve it.
Shooting a water arrow into or near a vine will cause it to grow where hit.