Your options for hierarchy are tree and advanced datagrid.
Check out rendererproviders for advanced data grid. You specify which renderer to use based on the hierarchy depth. Turn off ADG headers, row colors, and borders if you want no chrome.
<mx:AdvancedDataGrid
id="myDatagrid">
<mx:columns>
<mx:AdvancedDataGridColumn />
</mx:columns>
<mx:rendererProviders>
<mx:AdvancedDataGridRendererProvider
renderer="com.somepath.someclass"
columnSpan="0"
columnIndex="0"
depth="1"/>
<mx:AdvancedDataGridRendererProvider
renderer="com.somepath.someotherclass"
columnIndex="0"
columnSpan="0"
depth="2"/>
</mx:rendererProviders>
</mx:AdvancedDataGrid >