Complex sentence: About 4,100 species in approximately 19 families of flowering plants are either partly or completely parasitic on other plants Nickrent, D. L. and Musselman, L. J.2004.
Split into simpler sentences: About 4,100 species in approximately 19 families of flowering plants are parasitic plants. They are either partly or completely parasitic on other plants Nickrent, D. L. and Musselman, L. J.2004.