This species has been misunderstood in habitat and in cultivation. For many years tomaselli was grouped with Dioon sonorense but the species are very different geographically and morphologically. Tomaselli resembles the large leaf dioon species and the leaflets are deflexed. The habitat is very extensive with plants from Jalisco south of Puerta Vallarta north through Nayarit to Durango, Mexico. Plants are found in arroyos where moisture is available in otherwise arid landscape. Few people have every tried tomaselli in cultivation however it can be very attractive given proper culture.