Boscage or Boskage
1. A mass of growing trees or shrubs; a thicket, grove; woody undergrowth; sylvan scenery.
2. The pictorial representation of wooded landscape.
Unsurprisingly this is derived via the Middle English boskage and Old French boscage, from the late Latin boscāticum, wooded country, a thicket.
Boscage is an ancient word with the OED recording the first written usage as early as 1400.