birchen

[bur-chuh n] /ˈbɜr tʃən/
adjective
1.
of or pertaining to birch.
2.
made or consisting of birch:
birchen furniture.
Origin
1400-50; late Middle English; see birch, -en2
Word Origin and History for birchen
adj.

mid-15c., from birch (n.) + -en (2).