1. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 35.18 Primary and secondary growth of a stem (layer 1) (a) Primary and secondary growth in a two-year-old stem Pith Primary xylem Vascular cambium Primary phloem Epidermis Cortex 1

2. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 35.18 Primary and secondary growth of a stem (layer 2) Vascular cambium 4 First cork cambium Pith Primary xylem Vascular cambium Primary phloem Epidermis Cortex 2 1 Growth Primary xylem Secondary xylem Primary phloem Cork Phloem ray 3 Xylem ray Secondary phloem (a) Primary and secondary growth in a two-year-old stem

3. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 35.18 Primary and secondary growth of a stem (layer 3) Vascular cambium Pith Primary xylem Secondary xylem Vascular cambium Secondary phloem Primary phloem Periderm (mainly cork cambia and cork) Pith Primary xylem Vascular cambium Primary phloem Cortex Epidermis Vascular cambium 4 First cork cambium Secondary xylem (two years of production) Pith Primary xylem Vascular cambium Primary xylem Epidermis Cortex 2 1 6 Growth Primary xylem Secondary xylem Secondary phloem Primary phloem Cork Phloem ray 3 Xylem ray Growth 9 Bark 8 Layers of periderm 7 Cork 5 Most recent cork cambium (a) Primary and secondary growth in a two-year-old stem Secondary phloem