This is a small order with 5 families and 3 genera. There is still much uncertainty about the families and members. Cardiopteridaceae members were formerly in other families, especially included in Icacinaceae. Cardiopteridaceae is rather diverse in spite of having only six genera. Cardiopteris is soemtimes put in its own family, the other five genera placed in Leptaulaceae. Phyllonoma has been placed in Grossulariaceae in the past. Helwingia has been connected with Cornaceae.
A possible connection to Subphases is the following.
1. Cardiopteridaceae: Cardiopteris, Citronella, Dendrobangia, Gonocaryum, Leptaulis, Peripterygium, Pseudobotrys.
2. Stemonuraceae: Cantleya, Codiocarpus, Discophora, Gastrolepis, Gomphandra, Grisollea, Irvingbaileya, Lasianthera, Medusanthera, Stemonurus, Urandra.
4. Aquifoliaceae: Ilex, Nemopanthus, Prinos.
5. Phyllonomaceae: Phyllonoma.
6. Helwingiaceae: Helwingia.