Complex sentence: In 1989 and again in 1996 surveys of the area identified 20 native plants, 27 weeds included in the native plants is the only remaining natural occurrence of Rottnest Island pine "(Callitris preissii)" on the mainland.
Split into simpler sentences: In 1989 and again in 1996 surveys of the area identified 20 native plants and 27 weeds. Included in the native plants is the only remaining natural occurrence of Rottnest Island pine "(Callitris preissii)" on the mainland.