“FLOWERING PLANTS are the most diverse group of plants ever to sit on the Earth,” says William Friedman of the University of Colorado at Boulder. But with no obvious evolutionary predecessors, where did they come from? And how did flowering plants get to be so different from “primitive” land plants, such as mosses, ferns and conifers? Tormented by the problem, Charles Darwin called it an “abominable mystery”.

http://www.newscientist.com/article/mg19025525.500-where-have-all-the-flowers-come-from.html