Plants have stems and leaves that connect the roots to the leaves and branches. Stems serve as food storage and support systems for plants. A stem supports plants when it is upright. These structures are also protected from external factors by the stems. Aerial stems and underground stems are the two types of stems in plants. Usually found in trees, aerial stems are long and grow deep into the soil, while underground stems help in storing food. Depending on the ability of trees to retain their leaves in the winter or not, they are also classified as deciduous or evergreen trees. Xylem and phloem make up a majority of the stem. Phloem provides the plant with food, while xylem transports water and nutrients to the leaves. An aerial stem has air spaces between its stem cells, which makes it strong enough to withstand wind pressure. It also has similarly sized cells that withstand gravity’s pressure.

Functions of Stem

• Stems play different roles depending on where they are found. In addition to serving as help structures, food processing facilities also serve many other purposes. Plant leaves enable sunlight to be converted into energy.
• The stems of plants, for instance, serve as both structural supports and storage frameworks.
• During cold weather or unfavourable weather patterns, leaves convert daylight into energy, which is converted into glucose, which is stored until necessary.
• Along with providing water and supplements to the leaves, the stems also support the leaves. As the roots are connected to the soil, they absorb moisture and nutrients.
• Moreover, the stem serves as a channel for water. Water is released from the leaves through tiny openings in the stems as it transpires.
• Water is retained in the stem before being released through openings over the leaves during transpiration.
• One of its purposes is to support and hold leaves, flowers, and natural products.
• In order to perform photosynthesis, the leaves need immediate daylight, which the stem provides. Additionally, the plan and location of leaves should consider a gas exchange.
• Water and minerals are transported in the plant by xylem and phloem, located in the stem’s vascular bundle.
• It acts like a place where fertilisation, preparation, and seed dispersal work occur and ensures plants bear flowers and natural products.
• Stems undergo alternation to store food and water.
• A few green stems contain chloroplasts and can perform photosynthesis.
• A few stems are transformed to complete vegetative spread, a form of agamic proliferation.

Anatomy of Dicot stem

A vascular group surrounds the substance in the Dicot stem. It is an open, bilateral, and joint vascular bundle. Furthermore, the dicotyledonous stems or dicot stems contain two cotyledon leaves or early leaves.

Epidermis

• Parenchymatous cells form a protective outermost layer without intercellular spaces.
• An epidermal layer with multicellular hairs (trichomes) enclose the external dividers of epidermal cells.

Cortex

• Some layers of collenchyma cells exist beneath the epidermis of the stem, which form the hypodermis, which, in turn, provides mechanical stability to the stem.
• With prominent intercellular spaces, there are several layers of chlorenchyma cells. Pitch-like channels also exist here.
• Parenchyma cells make up the third zone. This cell type stores food resources.

Endodermis: (Starch sheath)

• There are no intercellular spaces between the barrel-shaped cells in this layer, and the cells are arranged minimally.
• This layer is also called starch sheath due to the abundance of starch grains within these cells.

Stele

• There are pericycles, vessels, and piths in the stele.

Pericycle (Bundle)

• As a couple of layers of sclerenchyma cells occur between the endodermis and vascular groups, the pericycle takes place.

Vascular Bundles

• A vascular group in the stem of a dicot is organised around its essence in a ring.
• It has two complete rings, open and endarch rings.

Pith

• Intercellular spaces between the parenchyma cells make up the focal piece called the pith.
• Pith rays or medullary rays are the expansions between vascular packs.
• The piths store food for later use.

Anatomy of Monocot Stem

There are fibrous bundles of vessels close to the base on the monocot stem. Vascular bundles separate from parenchymatous ground tissue. Dicot stems surround Parenchyma cells in an area with bundles attached in a ring.

Epidermis

• The peripheral layer comprises single cells with thick epidermis-like skin filled with firmly stuffed parenchymatous cells.
• The epidermis does not proliferate.

Hypodermis

• Plants receive mechanical stability from the hypodermis, a couple of layers of sclerenchymatous cells under the epidermis.

Ground tissue

• Unlike endodermis, cortex, pericycle, and pith, it does not have a stem
• A few layers of intercellular spaces are arranged in parenchyma cells enclosing visible intercellular spaces at the surface of the ground tissue.
•  Food is stored in the ground tissue.

Vascular bundles

• The parenchyma ground tissue is dotted with vascular bundles.
• There are a variety of vascular bundles in the fringe segment, which are small and well organised.
• Around the middle are large, roughly organised packs.
• There is a sheath of sclerenchyma filaments surrounding each vascular bundle.
• Valves are categorised into conjoints, collaterals, endarchs, and closed.

Phloem: In monocot stems, phloem can be found in the form of sieve tubes and companion cells. Phloem parenchyma and filaments are absent.

Xylem: Two metaxylem vessels are found at the top of the stalks; a couple of protoxylem vessels are at the bottom. A protoxylem lacuna forms when the least protoxylem crumbles in a fully developed bundle.

Conclusion

Some stems grow underground, but most are above ground. A stem can be either unbranched or exceedingly spread; it can be herbaceous or woody. Roots and leaves are connected by stems, which help ship minerals, sugars, and water throughout the plant.