Hypericaceae
The segregation of Hypericaceae from Guttiferae is confirmed by recent molecular research (APG III). The latter has no representatives in Belgium.
The family is represented by a single genus in Belgium, Hypericum. A North American species from a second genus, Triadenum fraseri (Spach) Gleason, is known from a fen in western Germany - relatively close to the Belgian frontiers - since 2011 and looks firmly established (Klasing & al. 2016). A further expansion cannot be excluded.
Literature:
APG III (2009) An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants. APG III. Bot. J. Linn. Soc. 161(2): 105-121. [available online at: http://onlinelibrary.wiley.com/doi/10.1111/j.1095-8339.2009.00996.x/pdf]
Klasing L., Schwartze P., Loos G.H. & Jagel A. (2016) Frasers Auenhartheu (Triadenum fraseri, Hypericaceae) im Emsdettener Venn (Kreis Steinfurt, Nordrhein-Westfalen). Veröff. Bochumer Bot. Ver. 8(4): 25-28. [available online at: http://www.botanik-bochum.de/publ/OVBBV8_4_Klasing_Schwartze_Loos_Jagel_...