Note that where the chains meet, the parenchyma cells are branched. Small angular crystals are embedded in the walls of the sclereids. Vascular tissue . In the region of the veins, the spongy parenchyma cells form a compact tissue and sheath around the vascular tissues. Note the large proportion of phloem to xylem in the veins of this hydromorphic leaf.
Conifer leaves vary from needle-like to rather flattened structures.
The pine leaf, of course, is an example of a needle-like leaf. Epidermal cells with thick walls and cuticle. The guard cells are sunken and attached to prominent subsidiary cells . The outer cells of the ground tissue are differentiated as a hypodermis and are sclerenchymatous. In transverse sections the mesophyll appears compact but longitudinal sections would reveal prominent intercellular spaces.