A small genus of N. American plants closely allied to Hypericum, but well distinguished by having four sepals and petals instead of five.
From the Supplement (Vol. V)
Ascyrum is no longer recognised as a genus distinct from Hypericum, the tetramerous corolla characterising this group being of too trivial a nature to justify generic or even sectional rank. The species described – A. hypericoides L. – becomes H. hypericoides (L.) Crantz.