The difference between root and stem is due to the following properties like:
Origination: Roots originate from the radicle by the germination of seed whereas shoots originate from the plumule of developing the embryo.
Arrangement of vascular bundles: In roots, the vascular bundles are arranged in the central core while in shoots, arranged in a dispersed form.
Presence of nodes: Nodes are the growing point of the stem, which is absent in a root system.
Apart from many differences, there are also some similarities like:
The occurrence of vascular tissues: Both root and stem carry vascular tissues, i.e. xylem and phloem.
Branching: Both can initiate lateral growth to form branches.
Content: Root Vs Stem
|Definition||Root requisites in a plant’s root system that usually grows downwards the plant axis and bears lateral rootlets, root hairs and a root cap.||Stem requisites in a plant’s shoot system that grows aerially or upwards and bears lateral stems, stem hairs, leaves, buds, flowers etc.|
|Part of||Root system||Shoot system|
|Geotropism||Shows positive geotropism||Shows negative geotropism|
|Phototropism||Shows negative phototropism||Shows positive phototropism|
|Hydrotropism||Shows positive hydrotropism||Shows negative hydrotropism|
|Origination||Originates from radicle||Originates from plumule|
|Presence of leaves||Absent||Present|
|Presence of buds||Absent||Present|
|Presence of flowers and fruits||Absent||Present|
|Presence of nodes and internodes||Absent||Present|
|Presence of hairs||Root comprises of unicellular root hairs||Stem comprises of multicellular stem hairs|
|Existence of cap-like structure||Root consists of a cap-like structure refers as root cap||It lacks such kind of structure|
|Branches||Root branches are endogenous||Stem branches are exogenous|
|Colour||Non-green||It is generally green coloured, during its young stage|
|Stomata||Absent||Present usually in the epidermis|
|Epidermis||Absorptive in function||Protective in function|
|Sclerenchymatous hypodermis||Absent||Present below the epidermis|
|Chloroplast||Invariably absent||It may contain in the outer cells of ground tissue|
|Pericycle||It is usually 1-2 layered, which participates in the root formation and secondary growth||It is multi layered, which does not participate in the secondary growth|
|Vascular bundles||Radial arrangement||Conjoint and collateral arrangement|
|Secondary vascular growth||Mediated by conjunctive parenchyma and pericycle||Mediated by intra or inter fascicular cambium|
|Fibers||Absent||Xylem and phloem contain fibers|
|Functions||Helps in anchorage of plant and nutrient absorption from the soil||Helps in photosynthesis, conduction and storage of food|
Definition of Root
Roots can define as a part of a root system that grows downwards the plant axis or subterranean to the soil surface. It originates from the radicle of the growing seed as primary root and later gives off lateral branches as secondary or tertiary roots.
A layer of epidermis surrounds the root surface and typically consist of three zones. Root hair or piliferous zone lies at the topmost region of the root system and comprises of several outgrowths or unicellular root hairs. There is also a permanent zone that helps in anchoring and transporting nutrients to the plants.
A root elongation zone lies between the piliferous region and meristematic zone, and its functional role is to promote root length.
Zone of meristematic cells lies between the elongation zone and root cap. The meristematic cells undergo multiple cell divisions and differentiate into three layers:
Outer layer: Here, the meristematic cells differentiate into Epiblema and root cap
Middle layer: Here, the meristematic cells mature to form cortex.
Central zone: Here, the cells mature into the stele.
At the root tip, a root cap is present, produced by the dermatogen layer. A root cap performs a primary function by giving protection to the apical meristem against the harsh soil particles. It has the capacity to regenerate. In aquatic plants instead of the root cap, a loose root pocket is present.
Definition of Stem
Stems can define as a part of a shoot system that grows upright to the plant axis or superterranean to the soil surface. It originates from the plumule of the growing embryo as primary stem and later gives off lateral branches as secondary or tertiary stems.
Stems bear nodes (give rise to the formation of leaves) and internodes (separates two nodes). Stems also bear buds which can be terminal and lateral in position. A terminal bud grows towards the tip and refers as “Apical bud”, and a lateral bud grows laterally towards the axil of a leaf and refers as “Axillary bud”.
The primary growth of stem is promoted by the primary meristems (apical and intercalary meristem) at the tips and nodes of the stem. Secondary growth occurs in the secondary or lateral meristem, located in and around the vascular tissues by forming secondary vascular tissues and woody axis (bark).
Key Differences Between Root and Stem
- Root requisites in a plant’s root system that usually grows downwards the plant axis and bears lateral rootlets, root hairs and a root cap. Stem requisites in a plant’s shoot system that grows aerially or upwards and bears lateral stems, stem hairs, leaves, buds, flowers etc.
- Root emerges out from the first outgrowth of the developing seed or radicle. Stem emerges out from the plumule of the seed’s embryo.
- Stems are the part of the shoot system that flourishes above the soil surface and shows negative geotropism. Roots are the part of the root system that flourishes underground the soil and shows positive geotropism.
- Stems bend towards the light and are positively phototropic while roots are negatively phototropic.
- Roots are the tubular structures that move towards the water and shows positive hydrotropism, whereas stems are the branched structures that move away from the water and are negatively hydrotropic.
- A stem carries leaves, buds, flowers, fruits, nodes, internodes and terminal bud whereas a root system lacks all these.
- Multicellular stem hairs are present throughout the body of stem, whereas roots are always surrounded by unicellular root hairs.
- Thimble like root cap is a structure that is only found in a root system and differentiates it from the other parts of the plant.
- The growing point of the root is sub-terminal and give rise to the formation of endogenous root branches, while the growing point of the stem is terminal and give rise to the formation of exogenous stem branches.
- Cuticle, Schlerenchymatous hypodermis, stomata, chloroplast, fibres are absent in the cross-section view of the root system, while present in stems.
- The epidermis of root comprises of several root hairs that participate in water and mineral absorption and are absorptive in function. The epidermis of the stem is protective in function.
- Root possesses a broad cortex and stem possesses a narrow cortex.
- Stem usually possesses a multi-layered pericycle that does not participate in the secondary growth, whereas root possesses 1-2 layered pericycle that participates in the secondary growth.
- In roots, the vascular bundles have a radial arrangement and having exarch xylem. In stems, the vascular bundles are conjoint and collateral and having endarch xylem.
- The secondary growth of root is promoted by the conjunctive parenchyma and pericycle, whereas in stems, intra or interfascicular cambium promotes the growth.
- Root performs two functional roles like anchorage and nutrient absorption, whereas stem performs functions like preparation, transportation and storage of food in a plant system.
Therefore, we can conclude that without the working of roots and stems, a plant could not thrive as both perform different roles to maintain the plant physiology.