WordNet (r) 3.0 (2006):

treelike
    adj 1: resembling a tree in form and branching structure;
           "arborescent coral found off the coast of Bermuda";
           "dendriform sponges" [syn: arboreal, arboreous,
           arborescent, arboresque, arboriform, dendriform,
           dendroid, dendroidal, treelike, tree-shaped]

Moby Thesaurus II by Grady Ward, 1.0:

44 Moby Thesaurus words for "treelike":
   V-shaped, Y-shaped, arborary, arboreal, arboreous, arborescent,
   arboresque, arborical, arboriform, biforked, bifurcate, bifurcated,
   branched, branching, branchlike, bushlike, bushy, citrous,
   coniferous, crotched, deciduous, dendriform, dendritic, dendroid,
   evergreen, forked, forking, forklike, furcate, hardwood,
   nondeciduous, piny, pronged, ramous, scrubbly, scrubby, scrublike,
   shrubby, shrublike, softwood, tree-shaped, tridentlike, trifurcate,
   trifurcated