diff --git a/bench/Bench.hs b/bench/Bench.hs
--- a/bench/Bench.hs
+++ b/bench/Bench.hs
@@ -4,6 +4,7 @@
 import           Data.TreeBench
 import           Data.Tree.SetBench
 import           Data.Tree.KnuthBench
+import           Data.Tree.HashBench
 import           Criterion.Main
 
 
@@ -14,5 +15,6 @@
     [ data_tree_bench
     , data_settree_bench
     , data_knuthtree_bench
+    , data_hashtree_bench
     ]
   ]
diff --git a/bench/Data/Build.hs b/bench/Data/Build.hs
new file mode 100644
--- /dev/null
+++ b/bench/Data/Build.hs
@@ -0,0 +1,37 @@
+{-# LANGUAGE
+    GADTs
+  , FlexibleContexts
+  #-}
+
+module Data.Build where
+
+import Data.Tree.Rose
+import Control.Monad.State
+
+
+newNode :: ( MonadState Int m
+           , RoseTree t
+           , Head (t Int) ~ Int
+           ) => Tail (t Int)
+             -> m (t Int)
+newNode xs = do
+  x <- get
+  modify (+1)
+  return $ x @-> xs
+
+makeWith :: ( MonadState Int m
+            , Head (t Int) ~ Int
+            , RoseTree t
+            ) => Int -- Depth
+              -> Int -- Width
+              -> Int -- Ratio
+              -> Tail (t Int)
+              -> ([t Int] -> Tail (t Int))
+              -> m (t Int)
+makeWith d w r empty fromList
+  | d <= 1    = newNode empty
+  | otherwise = do
+      xs <- replicateM w $
+              makeWith (d-1) (floor $ (fromIntegral w :: Float)
+                                    / fromIntegral r) r empty fromList
+      newNode $ fromList xs
diff --git a/bench/Data/Tree/HashBench.hs b/bench/Data/Tree/HashBench.hs
new file mode 100644
--- /dev/null
+++ b/bench/Data/Tree/HashBench.hs
@@ -0,0 +1,41 @@
+{-# LANGUAGE
+    FlexibleContexts
+  #-}
+
+module Data.Tree.HashBench (data_hashtree_bench) where
+
+import Data.Build
+import Prelude hiding (elem)
+import Data.Monoid
+import qualified Data.HashSet as HS
+import Data.Tree.Hash
+import Control.Monad.State
+import Criterion
+
+
+tree1 = evalState (makeWith 10 10 2 HS.empty HS.fromList) 1
+tree2 = evalState (makeWith 20 20 2 HS.empty HS.fromList) 1
+tree3 = evalState (makeWith 30 30 2 HS.empty HS.fromList) 1
+tree4 = evalState (makeWith 40 40 2 HS.empty HS.fromList) 1
+tree5 = evalState (makeWith 50 50 2 HS.empty HS.fromList) 1
+
+
+data_hashtree_bench = bgroup "Data.Tree.Hash"
+  [ bgroup "depth"
+    [ bench "1" $ whnf maximum' tree1
+    , bench "2" $ whnf maximum' tree2
+    , bench "3" $ whnf maximum' tree3
+    , bench "4" $ whnf maximum' tree4
+    , bench "5" $ whnf maximum' tree5
+    ]
+  , bgroup "width"
+    [ bench "1" $ whnf maximum' tree1
+    , bench "2" $ whnf maximum' tree2
+    , bench "3" $ whnf maximum' tree3
+    , bench "4" $ whnf maximum' tree4
+    , bench "5" $ whnf maximum' tree5
+    ]
+  ]
+
+maximum' :: HashTree Int -> Int
+maximum' = maximum
diff --git a/bench/Data/Tree/KnuthBench.hs b/bench/Data/Tree/KnuthBench.hs
--- a/bench/Data/Tree/KnuthBench.hs
+++ b/bench/Data/Tree/KnuthBench.hs
@@ -25,26 +25,29 @@
                                 modify (+1)
                                 return $ F.Fork x xs ws
 
-tree1 = evalState (makeWith 1 1 2 >>= newNode) 1
-tree2 = evalState (makeWith 2 2 2 >>= newNode) 1
-tree3 = evalState (makeWith 3 3 2 >>= newNode) 1
-tree4 = evalState (makeWith 4 4 2 >>= newNode) 1
-tree5 = evalState (makeWith 5 5 2 >>= newNode) 1
+tree1 = evalState (makeWith 10 10 2 >>= newNode) 1
+tree2 = evalState (makeWith 20 20 2 >>= newNode) 1
+tree3 = evalState (makeWith 30 30 2 >>= newNode) 1
+tree4 = evalState (makeWith 40 40 2 >>= newNode) 1
+tree5 = evalState (makeWith 50 50 2 >>= newNode) 1
 
 
 data_knuthtree_bench = bgroup "Data.Tree.Knuth"
   [ bgroup "depth"
-    [ bench "1" $ whnf (elem 1) tree1
-    , bench "2" $ whnf (elem 2) tree2
-    , bench "3" $ whnf (elem 5) tree3
-    , bench "4" $ whnf (elem 18) tree4
-    , bench "5" $ whnf (elem 23) tree5
+    [ bench "1" $ whnf maximum' tree1
+    , bench "2" $ whnf maximum' tree2
+    , bench "3" $ whnf maximum' tree3
+    , bench "4" $ whnf maximum' tree4
+    , bench "5" $ whnf maximum' tree5
     ]
   , bgroup "width"
-    [ bench "1" $ whnf (elem 1) tree1
-    , bench "2" $ whnf (elem 2) tree2
-    , bench "3" $ whnf (elem 6) tree3
-    , bench "4" $ whnf (elem 20) tree4
-    , bench "5" $ whnf (elem 25) tree5
+    [ bench "1" $ whnf maximum' tree1
+    , bench "2" $ whnf maximum' tree2
+    , bench "3" $ whnf maximum' tree3
+    , bench "4" $ whnf maximum' tree4
+    , bench "5" $ whnf maximum' tree5
     ]
   ]
+
+maximum' :: KnuthTree Int -> Int
+maximum' = maximum
diff --git a/bench/Data/Tree/SetBench.hs b/bench/Data/Tree/SetBench.hs
--- a/bench/Data/Tree/SetBench.hs
+++ b/bench/Data/Tree/SetBench.hs
@@ -4,6 +4,7 @@
 
 module Data.Tree.SetBench (data_settree_bench) where
 
+import Data.Build
 import Prelude hiding (elem)
 import Data.Monoid
 import qualified Data.Set as Set
@@ -12,36 +13,30 @@
 import Criterion
 
 
-newNode :: MonadState Int m => Set.Set (SetTree Int) -> m (SetTree Int)
-newNode xs = do x <- get
-                modify (+1)
-                return $ SetTree x xs
 
--- makeWith :: Int -> Int -> Int -> State Int (Tree Int)
-makeWith d w r | d <= 1 = newNode Set.empty
-               | otherwise = do xs <- replicateM w $ makeWith (d-1) (floor $ fromIntegral w / r) r
-                                newNode $ Set.fromList xs
-
-tree1 = evalState (makeWith 1 1 2) 1
-tree2 = evalState (makeWith 2 2 2) 1
-tree3 = evalState (makeWith 3 3 2) 1
-tree4 = evalState (makeWith 4 4 2) 1
-tree5 = evalState (makeWith 5 5 2) 1
+tree1 = evalState (makeWith 10 10 2 Set.empty Set.fromList) 1
+tree2 = evalState (makeWith 20 20 2 Set.empty Set.fromList) 1
+tree3 = evalState (makeWith 30 30 2 Set.empty Set.fromList) 1
+tree4 = evalState (makeWith 40 40 2 Set.empty Set.fromList) 1
+tree5 = evalState (makeWith 50 50 2 Set.empty Set.fromList) 1
 
 
 data_settree_bench = bgroup "Data.Tree.Set"
   [ bgroup "depth"
-    [ bench "1" $ whnf (elem 1) tree1
-    , bench "2" $ whnf (elem 2) tree2
-    , bench "3" $ whnf (elem 5) tree3
-    , bench "4" $ whnf (elem 18) tree4
-    , bench "5" $ whnf (elem 23) tree5
+    [ bench "1" $ whnf maximum' tree1
+    , bench "2" $ whnf maximum' tree2
+    , bench "3" $ whnf maximum' tree3
+    , bench "4" $ whnf maximum' tree4
+    , bench "5" $ whnf maximum' tree5
     ]
   , bgroup "width"
-    [ bench "1" $ whnf (elem 1) tree1
-    , bench "2" $ whnf (elem 2) tree2
-    , bench "3" $ whnf (elem 6) tree3
-    , bench "4" $ whnf (elem 20) tree4
-    , bench "5" $ whnf (elem 25) tree5
+    [ bench "1" $ whnf maximum' tree1
+    , bench "2" $ whnf maximum' tree2
+    , bench "3" $ whnf maximum' tree3
+    , bench "4" $ whnf maximum' tree4
+    , bench "5" $ whnf maximum' tree5
     ]
   ]
+
+maximum' :: SetTree Int -> Int
+maximum' = maximum
diff --git a/bench/Data/TreeBench.hs b/bench/Data/TreeBench.hs
--- a/bench/Data/TreeBench.hs
+++ b/bench/Data/TreeBench.hs
@@ -4,6 +4,7 @@
 
 module Data.TreeBench (data_tree_bench) where
 
+import Data.Build
 import Data.Monoid
 import Data.Tree
 import Data.Tree.Rose
@@ -11,39 +12,29 @@
 import Criterion
 
 
-newNode :: MonadState Int m => [Tree Int] -> m (Tree Int)
-newNode xs = do x <- get
-                modify (+1)
-                return $ Node x xs
-
--- makeWith :: Int -> Int -> Int -> State Int (Tree Int)
-makeWith d w r | d <= 1 = newNode []
-               | otherwise = do xs <- replicateM w $ makeWith (d-1) (floor $ (fromIntegral w) / r) r
-                                newNode xs
-
-tree1 = evalState (makeWith 1 1 2) 1
-tree2 = evalState (makeWith 2 2 2) 1
-tree3 = evalState (makeWith 3 3 2) 1
-tree4 = evalState (makeWith 4 4 2) 1
-tree5 = evalState (makeWith 5 5 2) 1
+tree1 = evalState (makeWith 10 10 2 [] id) 1
+tree2 = evalState (makeWith 20 20 2 [] id) 1
+tree3 = evalState (makeWith 30 30 2 [] id) 1
+tree4 = evalState (makeWith 40 40 2 [] id) 1
+tree5 = evalState (makeWith 50 50 2 [] id) 1
 
 
 data_tree_bench = bgroup "Data.Tree"
   [ bgroup "depth"
-    [ bench "1" $ whnf (elemT 1) tree1
-    , bench "2" $ whnf (elemT 2) tree2
-    , bench "3" $ whnf (elemT 5) tree3
-    , bench "4" $ whnf (elemT 18) tree4
-    , bench "5" $ whnf (elemT 23) tree5
+    [ bench "1" $ whnf maximum' tree1
+    , bench "2" $ whnf maximum' tree2
+    , bench "3" $ whnf maximum' tree3
+    , bench "4" $ whnf maximum' tree4
+    , bench "5" $ whnf maximum' tree5
     ]
   , bgroup "width"
-    [ bench "1" $ whnf (elemT 1) tree1
-    , bench "2" $ whnf (elemT 2) tree2
-    , bench "3" $ whnf (elemT 6) tree3
-    , bench "4" $ whnf (elemT 20) tree4
-    , bench "5" $ whnf (elemT 25) tree5
+    [ bench "1" $ whnf maximum' tree1
+    , bench "2" $ whnf maximum' tree2
+    , bench "3" $ whnf maximum' tree3
+    , bench "4" $ whnf maximum' tree4
+    , bench "5" $ whnf maximum' tree5
     ]
   ]
 
-elemT :: Eq a => a -> Tree a -> Bool
-elemT x (Node y ys) = x == y || getAny (foldMap (Any . elemT x) ys)
+maximum' :: Tree Int -> Int
+maximum' = maximum
diff --git a/rose-trees.cabal b/rose-trees.cabal
--- a/rose-trees.cabal
+++ b/rose-trees.cabal
@@ -1,5 +1,5 @@
 Name:                   rose-trees
-Version:                0.0.4.1
+Version:                0.0.4.2
 Author:                 Athan Clark <athan.clark@gmail.com>
 Maintainer:             Athan Clark <athan.clark@gmail.com>
 License:                BSD3
@@ -48,11 +48,13 @@
                       , deepseq
                       , rose-trees
                       , containers
+                      , hashable
                       , semigroups
                       , semigroupoids
                       , sets
                       , tasty
                       , tasty-quickcheck
+                      , unordered-containers
                       , witherable
                       , QuickCheck
                       , quickcheck-instances
@@ -71,14 +73,18 @@
                         Data.TreeBench
                         Data.Tree.SetBench
                         Data.Tree.KnuthBench
+                        Data.Tree.HashBench
+                        Data.Build
   Build-Depends:        base
                       , deepseq
                       , rose-trees
                       , containers
+                      , hashable
                       , mtl
                       , semigroups
                       , semigroupoids
                       , sets
+                      , unordered-containers
                       , witherable
                       , QuickCheck
                       , quickcheck-instances
diff --git a/test/Data/Tree/RoseSpec.hs b/test/Data/Tree/RoseSpec.hs
--- a/test/Data/Tree/RoseSpec.hs
+++ b/test/Data/Tree/RoseSpec.hs
@@ -8,6 +8,8 @@
 import qualified Data.Tree.Set as S
 import qualified Data.Tree.Knuth as K
 import qualified Data.Tree.Knuth.Forest as KF
+import qualified Data.Tree.Hash as HT
+import qualified Data.HashSet as HS
 
 
 import Test.Tasty
@@ -27,6 +29,9 @@
   , testGroup "Data.Tree.Knuth"
     [ QC.testProperty "element after construction" prop_cons_exists_KnuthTree
     ]
+  , testGroup "Data.Tree.Hash"
+    [ QC.testProperty "element after construction" prop_cons_exists_HashTree
+    ]
   ]
 
 newtype TreeWithElem t e = TreeWithElem {unTreeWithElem :: (e, t e)}
@@ -41,6 +46,9 @@
 
 prop_cons_exists_KnuthTree :: Int -> KF.KnuthForest Int -> Bool
 prop_cons_exists_KnuthTree x xs = K.elem x $ x @-> xs
+
+prop_cons_exists_HashTree :: Int -> HS.HashSet (HT.HashTree Int) -> Bool
+prop_cons_exists_HashTree x xs = HT.elem x $ x @-> xs
 
 
 -- instance (Arbitrary e