Weirwood

Weir trees resemble oaks but have leaves that are brown (with a silver sheen) on their uppers and velvety black beneath. If undisturbed, weir trees grow into huge, many-branched forest giants. Weirwood won't ignite in normal (nonmagical) fire and is resilient and durable. It's favored in the making of musical instruments because of the unmistakable warm, clear tone it imparts.

Weirwood can be used as a replacement for oak or holly in any spell. It grows throughout Faerun but is very rare. Most trees are now found deep in large forests and actively protected by dryads, treants, druids, and rangers.