Sentence:  Distinguished from other genera, with <WSD>accumbent</WSD> cotyledons, in the same class and order, by the entire, nearly equal "petals"; and the dehiscent, nearly entirely "pouch", of 2, 1- or many-seeded cells, a broad dissepiment (septum), and nearly flat valves. 
Meaning of the word marked with <WSD> tags:  Lying against anything, as one part of a leaf against another leaf