FLAT BIG LEAVES. “The vast majority of the estimated 250 000 or so extant species of flowering plants, as well as most gymnosperms and (extinct) pteridosperms, utilize(d) a flat-bladed megaphyll with a network of veins to capture solar energy for photosynthetic carbon assimilation.”
http://aob.oxfordjournals.org/content/96/3/345.full.pdf