The bioactivity-directed isolation of 4-hydroxy-3'-methoxybibenzyl [1] from a New Zealand liverwort, Plagiochila stephensoniana, is described. Compound 1 exhibited antifungal and antibacterial activity. Compound 1 is not considered to be a useful taxonomic marker. Syntheses of 1, stilbenes 2 and 3, and some derivatives were made and the biological activities were compared.