On Botany is named stem to that aerial part of all plants and that supports the leaves, flowers or fruits that these produce.
So, the main functions that the stem fulfills are that of support and transport of carbohydrates and other compounds, which are produced during the process of photosynthesis (conversion of inorganic into organic matter thanks to the energy of light), between the roots and the leaves.
The differences it presents with respect to the root is, on the one hand, the presence of knots in which the axillary buds and leaves will be inserted and, on the other hand, the negative geotropism that it shows and that makes it grow against gravity.
Among the variety of plants that exist, there are some species that have a single stem whose stem does not branch while there are others whose stem branches in different ways.
Meanwhile, the stem is composed of three tissue systems: the dermal, the fundamental and the vascular or fascicular.
The stems are classified from various points of view such as: by his habit on: epigeal or aerial (they grow above the ground), hypogea or underground (those that, on the contrary of the previous ones, grow under the ground such as tubers, bulbs, corms and rhizomes), for its consistency in: herbaceous (those that never develop adult or secondary tissues for which they have a soft and fragile consistency, such as scape, reed, calamus, fickle and climber) and woody (They are rigid and hard stems and without green color because they do not have chlorophyll, such as: shrub, arboreal and stipe ; and for the structural modifications that they present in: stem tendril, stem thorn and stolon.
For their part, photosynthetic stems They are those that assumed the function of the leaves and are typical of plants, which as a consequence of an adaptive factor stopped forming leaves.
It should be noted that many stem species are of outstanding economic importance, especially because provide food for humans, such is the case of the potato, taro, sugar cane, asparagus, cinnamon, bamboo shoots and hearts of palm hearts, among others.
And the brain stem, also called brainstem , is the junction of the midbrain, the annular pons and the medulla oblongata; It is the major communication pathway between the forebrain, peripheral nerves, and the spinal cord and controls functions such as: breathing, heart rate regulation, and early aspects of sound localization.
