Zanzibar gem, better known in U.S. homes as the ZZ plant, is a houseplant with glossy leaves. Its thick underground stems store water.
Cardboard palm has stiff, leathery leaflets rising from a short, thick trunk. ZZ plant has glossier leaflets on fleshy upright stalks that rise from underground stems.
Why they get mixed upBoth have rows of leaflets on upright leaves.