The time interval between the development of two of these structures is the plastochron. The evolution of large examples of these structures is the subject of the enation theory and telome theory. These structures have adaxial and abaxial sides. (10[1])These structures can be arranged as alternate or opposite, and their vasculature (10[2])can be reticulate, parallel, pinnate, or palmate. (10[1])Sessile (10[1])examples of these structures don't (10[1])have an attached petiole. A cross-section (10[1])of these structures shows their palisade and spongy mesophyll. The undersides of these (10[1])structures contain (10[1])guard cells flanking openings called stomata, which allow water loss through transpiration. Deciduous plants undergo abscission, or the loss of these structures. For 10 points, name these chlorophyll-containing structures responsible for photosynthesis in plants. ■END■