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Cross-section through the leaf of pine
Legend:
1 epidermis
3 sclerenchym
4 chlorenchym
5 vascular bundle
2 resin duct
6 tranfusion tissue
English name: Pine
Scientific name: Pinus sp.
Familia: Pinaceae
Classis: Coniferopsida
Phylum: Gymnospermae
Regnum: Plantae
This sample has been made of a freshly harvested needle. This is why the green color of chlorophyll in the chlorenchym is so obvious. The needles (kind of leaves) of gymnosperms like pine show great adaptations to living conditions in a dry environment. They have a relatively small but very strong epidermis with thick cell wall. The stomata are located at the flat side of the needle and are a bit enclosed. The area where evaporation can occur is limited due to the compact shape of the needle. For the same reason the distance between cells involved in gas exchange is small, so that small intercellular cavities between chlorenchym cells are sufficient to carry out. The needles contain large resin ducts. Only one of the two vascular bundles can been seen. The bundle is associated with supporting tissue (sclerenchyma). The central part of the leaf around the vessel has no chlorophyll and is thus not greenish; it is filled with parenchyma cells with large stipples. This tissue is called transfusion tissue and it is involved in transporting water from the vessel (xylem) to the chlorenchym.
