The Collaborative International Dictionary of English v.0.48:
Birchen \Birch"en\ (b[~e]rch"'n), a. Of or relating to birch. [1913 Webster] He passed where Newark's stately tower Looks out from Yarrow's birchen bower. --Sir W. Scott. [1913 Webster]WordNet (r) 3.0 (2006):
birchen adj 1: consisting of or made of wood of the birch tree [syn: birch, birchen, birken]