Fig. 3.2-3. Longitudinal section of the shoot tip of coleus (Coleus). This shoot tip will provide help you understand the orientation of Fig. 3.2-4, which is a close-up of the shoot apical meristem present here at the center of the image (the mass of very dark cells, labeled SAM)). There are two small leaf primordia, one on either side of the apical meristem, and to the outside of them are two much larger leaf primordia that are attached lower on the stem (three of the leaf primordia are indicated by arrows).