STEMS

HERBACEUS PLANTS

Herbaceous plants are plants that lack wood & bark. Instead they have soft green stems with central pith made up of vascular tissue. Many times these plants die after flowering. Monocots are all herbaceous, herbaceous dicot plants are known as Forbs.

WOODY PLANTS

Wood is made up of the dead rigid vascular tissues (Xylem & Phloem) to create a strong flexible structure. Plants evolved wood so that they could create larger more permanent structures. Most woody plants are perennial. Wood itself is dead, only a thin layer of living tissue exists between the wood & the bark. This living tissue is referred to as to cambium. Rings form in the wood from alternating growing & dormant seasons.

BARK

Bark is the outermost layer of the stems of woody plants. Just below the bark lies the vascular tissue or cambium, below this lies the wood of the stem. Inner bark is living creating layer upon layer of cells which die harden forming the outer protective bark.

STEMS THAT PHOTOSYNTHESIZE

Some plants have lost their leaves to evolution under certain climatic stresses in their environments. These plants moved the cells that photosynthesize into the surface of the plants stems. Some plants that are deciduous have secondary photosynthetic cells in their stems to produce food until new foliage is produced.

STEM ADAPTATIONS TO MOISTURE RETENTION

Stems of some plants have evolved to store water for use during times of drought. Many of these plants have reduced or no leafs, this helps to minimize water loss.

STEM ADAPTATIONS TO LOW NUTRIENT ENVIRONMENTS

Plants in low nutrient environments have often teamed up with insects to create a beneficial relationship between both the plant & the Insect. Ants play an important role with many of these plants. These plants often have developed hollow stems that the ants live in. The plants absorb the nutrients left behind by the ant colony.