Maidenhair tree (Ginkgo biloba) petiole. Light micrograph of a section through a petiole (leaf stalk) from a maidenhair tree (Ginkgo biloba), showing its thick cuticle and thick-walled epidermis (red) and hypodermis (subcutaneous tissue, light-brown). Stomata (pores) and guard cells can also be seen, along with chloroplasts, and mesophyll tissue composed of parenchyma cells (blue-brown). The vascular tissue is composed of xylem tracheid cells (red) and phloem sieve tube cells (brown). Magnification: x13 when printed 10 centimetres wide.