Q.What is Pith?
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🔒 Start your 14-day free trial to unlock the full solution →Concept understanding — Ground Tissue System
The Intuition: The "Filler" That Does the Real Work
Think of a plant stem or root as a city. The epidermis is the outer wall — protection. The vascular bundles (xylem and phloem) are the highways and power lines — transport. But what fills the space between the wall and the highways? What cushions everything, stores food, and sometimes even helps the plant stand upright?
That's the ground tissue system. It's everything that isn't the dermal (skin) or vascular (plumbing) system. In a young dicot stem, if you cut a cross-section, the ground tissue is the vast, continuous mass of cells you see packing the region from just beneath the epidermis all the way to the centre.
The Precise Statement
Ground Tissue System: All tissues of the plant body except the epidermis (dermal system) and the vascular bundles (vascular system). It includes the cortex, pericycle, pith, and medullary rays.
This system is not a single tissue type — it's a collection of tissues (mostly parenchyma, sometimes collenchyma or sclerenchyma) that perform storage, photosynthesis, support, and secretion.
Breaking Down the Components (in a typical dicot stem)
Imagine a young sunflower stem. From outside to inside:
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Cortex — The region between the epidermis and the vascular bundles. It's often divided into:
- Hypodermis (just under the epidermis): usually collenchyma — gives flexible support.
- General cortex: parenchyma cells — store starch, sometimes contain chloroplasts for photosynthesis.
- Endodermis (innermost layer of cortex): a single layer of cells that often contains starch grains (called the starch sheath). It acts as a selective barrier.
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Pericycle — A thin layer (one to a few cells thick) just inside the endodermis, but outside the vascular bundles. In roots, it's meristematic (can give rise to lateral roots). In stems, it's often sclerenchyma (fibres) — providing mechanical strength.
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Pith — The central region, inside the ring of vascular bundles. Made of large, thin-walled parenchyma cells. Stores food and water. In some plants, the pith dies and dries out, forming a hollow stem (like in many grasses).
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Medullary Rays — Also called pith rays. These are strips of parenchyma that run radially between the vascular bundles, connecting the pith to the cortex. They allow lateral transport of water and nutrients.
In monocot stems (like maize), the ground tissue is not neatly layered. Vascular bundles are scattered throughout the ground tissue, so there is no distinct cortex, pericycle, or pith — the entire interior is one continuous ground tissue.
Why This Matters for Exams
- Cortex and pith are always part of the ground tissue system. …
Pith is the central-most ground tissue of a stem (or root, where present), made of parenchyma cells that mainly store food and provide some mechanical support. …
Pith is the innermost ground tissue of the stem, composed of parenchyma cells, mainly meant for food storage.
In a typical dicot stem cross-section, the tissues from outside to inside are: epidermis, cortex (with hypodermis, general cortex, and endodermis), the ring of vascular bundles, and finally the pith at the very centre. The pith is composed of large, thin-walled, loosely arranged parenchyma cells with intercellular spaces. Its main functions are storage of food materials (starch, and sometimes other reserves) and, because the cells are turgid, it also provides some mechanical support to the young stem. In some plants the pith may break down as the stem matures, leaving a hollow …
- CBSE 2026Set ANNUAL1 markMCQQ.Passage cells are found in -(a) Ectoderm(b) Endoderm(c) Pericycle(d) Lenticels
›Reveal solutionSolution
Passage cells are a special category of endodermal cells that stay thin-walled and Casparian-strip-free, permitting continued water movement into the stele.
The endodermis is the innermost layer of the root cortex, encircling the stele. Young endodermal cells develop a band-like thickening of suberin on their radial and tangential (anticlinal) walls, called the Casparian strip, which forces water to cross the endodermis symplastically (through the cytoplasm) rather than through the walls.
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- CBSE 2025Set botany-sz1 markMCQQ.Which of the following is not the part of Ground tissue system ?(a) Epidermis(b) Cortex(c) Endodermis(d) Pericycle
›Reveal solutionSolution
Epidermis belongs to the epidermal (dermal) tissue system, not to the ground tissue system; cortex, endodermis and pericycle are all parts of the ground tissue system.
The three tissue systems of a plant, based on position, are:
- Epidermal (dermal) tissue system — the outermost covering of the plant body, made up of epidermal cells, stomata and epidermal appendages (trichomes, root hairs).
- Ground tissue system — all tissue lying between the epidermis on the outside and the vascular bundles on the inside. It comprises the cortex, endodermis, pericycle, pith and medullary rays, made up mainly of simple tissues (parenchyma, collenchyma, sclerenchyma).
- Vascular tissue system — the conducting tissue, xylem and phloem, arranged into vascular bundles. …
- CBSE 2025Set ANNUAL1 markMCQQ.The correct statement for endodermis is(a) They are present below the epidermis and are made up of collenchymatous cells.(b) They are few to many and made up of parenchymatous cells.(c) They are composed of single layer of vertically elongated cells and are present in dicot stems.(d) They maybe single layered or multilayered and are one cell thick in roots.
›Reveal solutionSolution
Endodermis is the innermost layer of the cortex; in roots it is invariably a single (one-cell-thick) layer, though in aerial stems of a few plants it can be multiseriate.
The endodermis forms the boundary between the cortex and the stele (vascular cylinder). Its cells are usually barrel-shaped, arranged compactly without intercellular spaces, and bear a band of suberised/waxy material on their radial and tangential walls called the Casparian strip, which forces water and solutes to cross a living membrane (apoplast-to-symplast switch) before entering the xylem.
Checking each option:
- (a) is wrong, a collenchymatous layer just below the epidermis describes the hypodermis of a dicot stem, not the endodermis.
- (b) is wrong, several layers of parenchymatous cells just internal to the endodermis describes the pericycle, not the endodermis. …
- CBSE 2022Set ANNUAL1 markQ.Casparian strips are found in ________. (Epidermis / Endodermis / Pericycle)
›Reveal solutionSolution
Casparian strips are a waxy (suberin) band found in the radial and transverse walls of endodermal cells in roots.
In the primary structure of a dicot root, the endodermis is a single layer of barrel-shaped cells forming the innermost boundary of the cortex, immediately surrounding the vascular (stele) tissue. Its radial and transverse walls (but not the tangential walls) contain a band of suberin, a waxy, impermeable substance, called the Casparian strip. Because this strip blocks the free (apoplastic) movement of water through the cell w …
- CBSE 2020Set ANN1 markQ.Choose the correct answer. Casparian strips are present in :
›Reveal solutionSolution
Casparian strips are waxy (suberin) bands present in the radial and transverse walls of endodermal cells surrounding the vascular tissue of a root; they are a feature of root anatomy, so the correct answer is Dicot root.
In the primary structure of a root, the innermost layer of the cortex is a single layer of compactly arranged cells called the endodermis, which encircles the vascular bundle (stele). Each endodermal cell wall (on its radial and transverse faces, not the tangential faces) develops a band-like thickening made of suberin, a waterproof fatty substance. This thickened band is called the Casparian strip.
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- CBSE 2020Set ANNUAL1 markQ.What is Pith?
›Reveal solutionSolution
Pith is the innermost ground tissue of the stem, composed of parenchyma cells, mainly meant for food storage.
In a typical dicot stem cross-section, the tissues from outside to inside are: epidermis, cortex (with hypodermis, general cortex, and endodermis), the ring of vascular bundles, and finally the pith at the very centre. The pith is composed of large, thin-walled, loosely arranged parenchyma cells with intercellular spaces. Its main functions are storage of food materials (starch, and sometimes other reserves) and, because the cells are turgid, it also provides some mechanical support to the young stem. In some plants the pith may break down as the stem matures, leaving a hollow …
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