Complex sentence: At one extreme, e.g. Cronquist system 1968, they have been regarded as one large family (Liliaceae), while at the other, e.g. Dahlgren system 1985 has conceived them as many orders and many small families.
Split into simpler sentences: At one extreme, e.g. the Cronquist system of 1968, they have been regarded as one large family (Liliaceae). At the other extreme, e.g. the Dahlgren system of 1985, they have been divided into orders and many small families.