diff --git a/src/chart_types/partition_chart/layout/utils/group_by_rollup.ts b/src/chart_types/partition_chart/layout/utils/group_by_rollup.ts
index 58efe0630c..05aae6c1ad 100644
--- a/src/chart_types/partition_chart/layout/utils/group_by_rollup.ts
+++ b/src/chart_types/partition_chart/layout/utils/group_by_rollup.ts
@@ -58,7 +58,7 @@ interface MapNode extends NodeDescriptor {
 }
 
 /** @internal */
-export const hierarchyRootKey: Key = '__root_key__';
+export const HIERARCHY_ROOT_KEY: Key = '__root_key__';
 
 export type PrimitiveValue = string | number | null; // there could be more but sufficient for now
 type Key = CategoryKey;
@@ -129,8 +129,8 @@ export function groupByRollup(
     });
     return p;
   }, new Map());
-  if (reductionMap.get(hierarchyRootKey) !== undefined) {
-    statistics.globalAggregate = (reductionMap.get(hierarchyRootKey) as MapNode)[AGGREGATE_KEY];
+  if (reductionMap.get(HIERARCHY_ROOT_KEY) !== undefined) {
+    statistics.globalAggregate = (reductionMap.get(HIERARCHY_ROOT_KEY) as MapNode)[AGGREGATE_KEY];
   }
   return reductionMap;
 }
diff --git a/src/chart_types/partition_chart/partition.test.tsx b/src/chart_types/partition_chart/partition.test.tsx
index 73b7513e52..05f257e8d5 100644
--- a/src/chart_types/partition_chart/partition.test.tsx
+++ b/src/chart_types/partition_chart/partition.test.tsx
@@ -23,7 +23,7 @@ import { MockSeriesSpec } from '../../mocks/specs';
 import { MockStore } from '../../mocks/store';
 import { GlobalChartState } from '../../state/chart_state';
 import { LegendItemLabel } from '../../state/selectors/get_legend_items_labels';
-import { hierarchyRootKey } from './layout/utils/group_by_rollup';
+import { HIERARCHY_ROOT_KEY } from './layout/utils/group_by_rollup';
 import { computeLegendSelector } from './state/selectors/compute_legend';
 import { getLegendItemsLabels } from './state/selectors/get_legend_items_labels';
 
@@ -98,7 +98,7 @@ describe('Retain hierarchy even with arbitrary names', () => {
           childId: 'A',
           color: 'rgba(128, 0, 0, 0.5)',
           path: [
-            { index: 0, value: hierarchyRootKey },
+            { index: 0, value: HIERARCHY_ROOT_KEY },
             { index: 0, value: 'A' },
           ],
           depth: 0,
@@ -109,7 +109,7 @@ describe('Retain hierarchy even with arbitrary names', () => {
           childId: 'A',
           color: 'rgba(128, 0, 0, 0.5)',
           path: [
-            { index: 0, value: hierarchyRootKey },
+            { index: 0, value: HIERARCHY_ROOT_KEY },
             { index: 0, value: 'A' },
             { index: 0, value: 'A' },
           ],
@@ -121,7 +121,7 @@ describe('Retain hierarchy even with arbitrary names', () => {
           childId: 'B',
           color: 'rgba(128, 0, 0, 0.5)',
           path: [
-            { index: 0, value: hierarchyRootKey },
+            { index: 0, value: HIERARCHY_ROOT_KEY },
             { index: 0, value: 'A' },
             { index: 1, value: 'B' },
           ],
@@ -133,7 +133,7 @@ describe('Retain hierarchy even with arbitrary names', () => {
           childId: 'B',
           color: 'rgba(128, 0, 0, 0.5)',
           path: [
-            { index: 0, value: hierarchyRootKey },
+            { index: 0, value: HIERARCHY_ROOT_KEY },
             { index: 1, value: 'B' },
           ],
           depth: 0,
@@ -144,7 +144,7 @@ describe('Retain hierarchy even with arbitrary names', () => {
           childId: 'A',
           color: 'rgba(128, 0, 0, 0.5)',
           path: [
-            { index: 0, value: hierarchyRootKey },
+            { index: 0, value: HIERARCHY_ROOT_KEY },
             { index: 1, value: 'B' },
             { index: 0, value: 'A' },
           ],
@@ -156,7 +156,7 @@ describe('Retain hierarchy even with arbitrary names', () => {
           childId: 'B',
           color: 'rgba(128, 0, 0, 0.5)',
           path: [
-            { index: 0, value: hierarchyRootKey },
+            { index: 0, value: HIERARCHY_ROOT_KEY },
             { index: 1, value: 'B' },
             { index: 1, value: 'B' },
           ],
@@ -168,7 +168,7 @@ describe('Retain hierarchy even with arbitrary names', () => {
           childId: 'C',
           color: 'rgba(128, 0, 0, 0.5)',
           path: [
-            { index: 0, value: hierarchyRootKey },
+            { index: 0, value: HIERARCHY_ROOT_KEY },
             { index: 2, value: 'C' },
           ],
           depth: 0,
@@ -179,7 +179,7 @@ describe('Retain hierarchy even with arbitrary names', () => {
           childId: 'A',
           color: 'rgba(128, 0, 0, 0.5)',
           path: [
-            { index: 0, value: hierarchyRootKey },
+            { index: 0, value: HIERARCHY_ROOT_KEY },
             { index: 2, value: 'C' },
             { index: 0, value: 'A' },
           ],
@@ -191,7 +191,7 @@ describe('Retain hierarchy even with arbitrary names', () => {
           childId: 'B',
           color: 'rgba(128, 0, 0, 0.5)',
           path: [
-            { index: 0, value: hierarchyRootKey },
+            { index: 0, value: HIERARCHY_ROOT_KEY },
             { index: 2, value: 'C' },
             { index: 1, value: 'B' },
           ],
@@ -211,7 +211,7 @@ describe('Retain hierarchy even with arbitrary names', () => {
           path: [
             {
               index: 0,
-              value: hierarchyRootKey,
+              value: HIERARCHY_ROOT_KEY,
             },
             {
               index: 0,
@@ -228,7 +228,7 @@ describe('Retain hierarchy even with arbitrary names', () => {
           path: [
             {
               index: 0,
-              value: hierarchyRootKey,
+              value: HIERARCHY_ROOT_KEY,
             },
             {
               index: 0,
@@ -256,7 +256,7 @@ describe('Retain hierarchy even with arbitrary names', () => {
           path: [
             {
               index: 0,
-              value: hierarchyRootKey,
+              value: HIERARCHY_ROOT_KEY,
             },
             {
               index: 0,
@@ -273,7 +273,7 @@ describe('Retain hierarchy even with arbitrary names', () => {
           path: [
             {
               index: 0,
-              value: hierarchyRootKey,
+              value: HIERARCHY_ROOT_KEY,
             },
             {
               index: 0,
diff --git a/src/chart_types/partition_chart/state/selectors/get_highlighted_shapes.ts b/src/chart_types/partition_chart/state/selectors/get_highlighted_shapes.ts
index 4ff31854b1..dc6e1c516b 100644
--- a/src/chart_types/partition_chart/state/selectors/get_highlighted_shapes.ts
+++ b/src/chart_types/partition_chart/state/selectors/get_highlighted_shapes.ts
@@ -93,7 +93,6 @@ export type LegendStrategy = $Values<typeof LegendStrategy>;
 const defaultStrategy: LegendStrategy = LegendStrategy.Key;
 
 /** @internal */
-// why is it called highlighted... when it's a legend hover related thing, not a hover over the slices?
 export const legendHoverHighlightNodes = createCachedSelector(
   [getSettingsSpecSelector, getHighlightedLegendItemPath, partitionGeometries],
   (specs, highlightedLegendItemPath, geoms): QuadViewModel[] => {
diff --git a/src/chart_types/partition_chart/state/selectors/get_legend_items_labels.ts b/src/chart_types/partition_chart/state/selectors/get_legend_items_labels.ts
index ce4e53fd68..9aedd42cbf 100644
--- a/src/chart_types/partition_chart/state/selectors/get_legend_items_labels.ts
+++ b/src/chart_types/partition_chart/state/selectors/get_legend_items_labels.ts
@@ -22,7 +22,7 @@ import createCachedSelector from 're-reselect';
 import { getChartIdSelector } from '../../../../state/selectors/get_chart_id';
 import { LegendItemLabel } from '../../../../state/selectors/get_legend_items_labels';
 import { getSettingsSpecSelector } from '../../../../state/selectors/get_settings_specs';
-import { CHILDREN_KEY, HierarchyOfArrays, hierarchyRootKey } from '../../layout/utils/group_by_rollup';
+import { CHILDREN_KEY, HierarchyOfArrays, HIERARCHY_ROOT_KEY } from '../../layout/utils/group_by_rollup';
 import { Layer } from '../../specs';
 import { getPieSpec } from './pie_spec';
 import { getTree } from './tree';
@@ -57,7 +57,7 @@ function flatSlicesNames(
       formattedValue = formatter ? formatter(key) : `${key}`;
     }
     // preventing errors from external formatters
-    if (formattedValue != null && formattedValue !== '' && formattedValue !== hierarchyRootKey) {
+    if (formattedValue != null && formattedValue !== '' && formattedValue !== HIERARCHY_ROOT_KEY) {
       // save only the max depth, so we can compute the the max extension of the legend
       keys.set(formattedValue, Math.max(depth, keys.get(formattedValue) ?? 0));
     }
diff --git a/src/chart_types/partition_chart/state/selectors/tree.ts b/src/chart_types/partition_chart/state/selectors/tree.ts
index aadd68cb96..2839720442 100644
--- a/src/chart_types/partition_chart/state/selectors/tree.ts
+++ b/src/chart_types/partition_chart/state/selectors/tree.ts
@@ -24,7 +24,7 @@ import { SpecTypes } from '../../../../specs';
 import { GlobalChartState } from '../../../../state/chart_state';
 import { getSpecsFromStore } from '../../../../state/utils';
 import { configMetadata } from '../../layout/config/config';
-import { childOrders, HierarchyOfArrays, hierarchyRootKey } from '../../layout/utils/group_by_rollup';
+import { childOrders, HierarchyOfArrays, HIERARCHY_ROOT_KEY } from '../../layout/utils/group_by_rollup';
 import { getHierarchyOfArrays } from '../../layout/viewmodel/hierarchy_of_arrays';
 import { isSunburst, isTreemap } from '../../layout/viewmodel/viewmodel';
 import { PartitionSpec } from '../../specs';
@@ -45,7 +45,7 @@ export const getTree = createCachedSelector(
     return getHierarchyOfArrays(
       data,
       valueAccessor,
-      [() => hierarchyRootKey, ...layers.map(({ groupByRollup }) => groupByRollup)],
+      [() => HIERARCHY_ROOT_KEY, ...layers.map(({ groupByRollup }) => groupByRollup)],
       sorter,
     );
   },