diff --git a/seacrowd/utils/constants.py b/seacrowd/utils/constants.py
index cb8c537bd..965701caf 100644
--- a/seacrowd/utils/constants.py
+++ b/seacrowd/utils/constants.py
@@ -5,6 +5,7 @@
 from seacrowd.utils.schemas import (
     image_text_features,
     kb_features,
+    tree_features,
     pairs_features,
     pairs_features_score,
     pairs_multi_features,
@@ -43,9 +44,17 @@ class Tasks(Enum):
     WORD_SENSE_DISAMBIGUATION = "WSD"
     COREFERENCE_RESOLUTION = "COREF"
 
+
+    # Tree
+    CONSTITUENCY_PARSING = "CONST_PAR"
+
+    # Single Text Classification
+    ASPECT_BASED_SENTIMENT_ANALYSIS = "ABSA"
+
     # Single Text Classification (single-label)
     ABUSIVE_LANGUAGE_PREDICTION = "ABL"
     DOMAIN_KNOWLEDGE_CLASSIFICATION = "DKC" # classification for non NLP-oriented label
+
     EMOTION_CLASSIFICATION = "EC"
     LANGUAGE_IDENTIFICATION = "LI"
     HOAX_NEWS_CLASSIFICATION = "HNC"
@@ -207,6 +216,7 @@ class Licenses(Enum):
 
 TASK_TO_SCHEMA = {
     Tasks.DEPENDENCY_PARSING: "KB",
+    Tasks.CONSTITUENCY_PARSING: "TREE",
     Tasks.WORD_SENSE_DISAMBIGUATION: "T2T",
     Tasks.WORD_ANALOGY: "T2T",
     Tasks.KEYWORD_EXTRACTION: "SEQ_LABEL",
@@ -276,6 +286,7 @@ class Licenses(Enum):
 
 SCHEMA_TO_FEATURES = {
     "KB": kb_features,
+    "TREE": tree_features,
     "QA": qa_features,
     "T2T": text2text_features,
     "TEXT": text_features(),
diff --git a/seacrowd/utils/schemas/__init__.py b/seacrowd/utils/schemas/__init__.py
index b517372e2..d95c8e4c4 100644
--- a/seacrowd/utils/schemas/__init__.py
+++ b/seacrowd/utils/schemas/__init__.py
@@ -1,5 +1,6 @@
 from .image_text import features as image_text_features
 from .kb import features as kb_features
+from .tree import features as tree_features
 from .pairs import features as pairs_features
 from .pairs import features_with_continuous_label as pairs_features_score
 from .pairs_multilabel import features as pairs_multi_features
@@ -19,6 +20,7 @@
 __all__ = [
     "image_text_features",
     "kb_features",
+    "tree_features",
     "pairs_features",
     "pairs_features_score",
     "pairs_multi_features",
diff --git a/seacrowd/utils/schemas/tree.py b/seacrowd/utils/schemas/tree.py
new file mode 100644
index 000000000..b84c062e9
--- /dev/null
+++ b/seacrowd/utils/schemas/tree.py
@@ -0,0 +1,115 @@
+"""\
+Tree Schema
+
+This schema assumes a document with subnodes elements
+and a tree hierarchy.
+
+For example:
+
+                    SUBNODE1 - word1
+                  //
+            NODE1 - SUBNODE2 - word2
+        //
+ROOT    -   NODE2 - SUBNODE3 - word3
+        \\
+            NODE3 - SUBNODE4 - word4
+                  \\
+                    SUBNODE5 - word5
+
+Schema structure:
+
+        "id": sentence_id,
+        "passage": {
+            "id": sentence_id,
+            "type": None,
+            "text": "word1 word2 word3 word4 word5"
+            "offsets": [0, 29]
+        },
+        "nodes": [
+            {
+                "id": 0,
+                "type": ROOT,
+                "text": "word1 word2 word3 word4 word5",
+                "offsets": [0, 29],
+                "subnodes": [1, 2, 3]
+            },
+            {
+                "id": 1,
+                "type": NODE1,
+                "text": "word1 word2",
+                "offsets": [0, 11],
+                "subnodes": [4, 5]
+            },
+            {
+                "id": 2,
+                "type": NODE2,
+                "text": "word3",
+                "offsets": [12, 17],
+                "subnodes": [6]
+            },
+            {
+                "id": 3,
+                "type": NODE3,
+                "text": "word4 word5",
+                "offsets": [18, 29],
+                "subnodes": [7, 8]
+            },
+            {
+                "id": 4,
+                "type": SUBNODE1,
+                "text": "word1",
+                "offsets": [0, 5],
+                "subnodes": []
+            },
+            {
+                "id": 5,
+                "type": SUBNODE2,
+                "text": "word2",
+                "offsets": [6, 11],
+                "subnodes": []
+            },
+            {
+                "id": 6,
+                "type": SUBNODE3,
+                "text": "word3",
+                "offsets": [12, 17],
+                "subnodes": []
+            },
+            {
+                "id": 7,
+                "type": SUBNODE4,
+                "text": "word4",
+                "offsets": [18, 23],
+                "subnodes": []
+            },
+            {
+                "id": 8,
+                "type": SUBNODE5,
+                "text": "word5",
+                "offsets": [24, 29],
+                "subnodes": []
+            }
+        ]
+"""
+import datasets
+
+features = datasets.Features(
+    {
+        "id": datasets.Value("string"),
+        "passage": {
+            "id": datasets.Value("string"),
+            "type": datasets.Value("string"),
+            "text": datasets.Sequence(datasets.Value("string")),
+            "offsets": datasets.Sequence(datasets.Value("int32")),
+        },
+        "nodes": [
+            {
+                "id": datasets.Value("string"),
+                "type": datasets.Value("string"),
+                "text": datasets.Value("string"),
+                "offsets": datasets.Sequence(datasets.Value("int32")),
+                "subnodes": datasets.Sequence(datasets.Value("string")),  # ids of subnodes
+            }
+        ],
+    }
+)