Bark is the outermost layer of stems and roots of woody plants. Plants with bark include trees, woody vines, and shrubs. Bark refers to all the tissues outside the vascular cambium and is a nontechnical term. It overlays the wood and consists of the inner bark and the outer bark. The inner bark, which in older stems is living tissue, includes the innermost layer of the periderm. The outer bark on older stems includes the dead tissue on the surface of the stems, along with parts of the outermost periderm and all the tissues on the outer side of the periderm. The outer bark on trees which lies external to the living periderm is also called the rhytidome.
The bark of Pinus thunbergii is made up of countless shiny layers.
Damaged bark of a cherry tree
Living tree bark enveloping barbed wire
Bark of mature mango (Mangifera indica) showing lichen growth
A stem is one of two main structural axes of a vascular plant, the other being the root. It supports leaves, flowers and fruits, transports water and dissolved substances between the roots and the shoots in the xylem and phloem, photosynthesis takes place here, stores nutrients, and produces new living tissue. The stem can also be called halm or haulm or culms.
Stem showing internode and nodes plus leaf petioles
This above-ground stem of Polygonum has lost its leaves, but is producing adventitious roots from the nodes.
Climbing stem of Senecio angulatus.
Decumbent stem in Cucurbita maxima.
