Aridae is the second Subclass of the Class Lilianae, Monocots.
Araceae is included in the Order Alismatales in the Apg3 classification.
In the plant theory Araceae is split off from Alismatales and placed in its own Order and Subclass.
It consists of one Order, Arales and one family Araceae.
The picture of Araceae is quite different from the other Alismatales and fits more into the Carbon series. Placement as the second Subclass, the Carbon series of the Monocots fits better.