Herniaria (Heterochiton), (Graebner & Mattf.) F. Hermann

Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A., 1964, Flora Europaea - Volume 1. Lycopodiaceae to Platanaceae, Cambridge University Press : 152

Subgen. Heterochiton (Graebner & Mattf.) F. Hermann . Perennial, woody at base. Upper stipules and bracts with purplish-black coloration over most of their surface. Flowers tetramerous. 2 opposite sepals more or less enclosing the other 2.