BiologyCBSE Class 11 · Anatomy of Flowering Plants

Tissue Systems and Vascular Bundles in Flowering Plants

Updated 17 October 2026 · Fact-checked

Based on structure and location, tissues form three tissue systems: epidermal (epidermis, stomata, root hairs, trichomes), ground (cortex, pericycle, pith, mesophyll) and vascular (xylem, phloem and cambium). Vascular bundles are radial (xylem and phloem on different radii, roots) or conjoint (on the same radius, stems and leaves), open (with cambium) or closed (without).

In radial bundles xylem and phloem sit on different radii; in conjoint bundles they share one radius, and only open ones have cambium between them.

Illustration drawn for QuestionBuddy.

Understand Tissue Systems and Vascular Bundles

Epidermal tissue system. The epidermis is the outermost layer, of elongated compactly arranged cells, usually single-layered. It bears a waxy cuticle that prevents water loss (absent in roots). Stomata regulate transpiration and gas exchange; each has two guard cells, bean-shaped in dicots and dumb-bell shaped in grasses; outer walls thin and inner walls thick. Some epidermal cells next to guard cells are subsidiary cells. The stomatal aperture, guard cells and subsidiary cells form the stomatal apparatus. Root hairs are unicellular elongations of root epidermal cells, absorbing water and minerals. Trichomes on the stem epidermis are usually multicellular, may be branched or unbranched, soft or stiff, and help prevent water loss.

Ground tissue system. All tissues except epidermis and vascular bundles: simple tissues such as parenchyma, collenchyma and sclerenchyma. In dicot stems and roots, it is cortex, pericycle and pith; in leaves, the ground tissue is mesophyll with chloroplasts.

Vascular tissue system. Xylem and phloem with cambium in dicots.

Xylem: conducts water and minerals; elements are tracheids, vessels, xylem fibres, xylem parenchyma. Protoxylem is the first formed, metaxylem later formed.
Phloem: conducts food; sieve tube elements, companion cells, phloem parenchyma, phloem fibres. Protophloem and metaphloem.

Types of vascular bundles.

Radial: xylem and phloem on different radii, alternating with non-conducting tissue between (roots).
Conjoint: xylem and phloem together on the same radius, as in stems and leaves. With phloem on the outer side of xylem, they are collateral.
Open: cambium present between xylem and phloem, so secondary growth is possible (dicot stem).
Closed: cambium absent, no secondary growth (monocot stem).

In dicot stems, xylem is endarch (protoxylem towards the pith); in roots it is exarch (protoxylem towards the periphery).

Anatomy of the dorsiventral (dicot) leaf. Epidermis on both surfaces with cuticle, stomata more on the lower surface; mesophyll differentiated into palisade parenchyma (adaxial, elongated cells at right angles) and spongy parenchyma (abaxial, oval or round, loosely arranged, with large intercellular spaces); vascular bundles in veins, surrounded by bundle sheath cells. In the isobilateral (monocot) leaf, stomata are on both surfaces equally, the mesophyll is not differentiated, and bulliform cells (large empty colourless cells on the upper epidermis) help in rolling the leaf to minimise water loss.

Table: dicot leaf versus monocot leaf. Mesophyll: differentiated versus undifferentiated. Stomata: mostly lower versus both. Bulliform cells: absent versus present.

Draw and label: a stomatal apparatus (guard cells, subsidiary cells, aperture, chloroplasts).

Tissue Systems and Vascular Bundles: key facts

Tissue systems: $E p i d er ma l ∣ G r o u n d ∣ V a sc u l a r$; Three systems
Bundle types: Radial roots
Conjoint stem, leaf
Open cambium
Closed no cambium; By arrangement
Guard cells: Dicot: bean-shaped | Grass: dumb-bell shaped; Stomata
Xylem position: $S t e m : e n d a r c h ∣ R oo t : e x a r c h$; Protoxylem
Leaf mesophyll: $D i co t : p a l i s a d e + s p o n g y ∣ M o n oco t : u n d i f f er e n t ia t e d$; Leaf anatomy

Radial	roots
Conjoint	stem, leaf
Open	cambium
Closed	no cambium

How to answer Tissue Systems and Vascular Bundles questions

Questions ask for the tissue system of a given cell, or compare bundles and leaves.

1Locate the tissue: outermost = epidermal; between epidermis and bundles = ground; xylem and phloem = vascular.
2For bundles, state arrangement (radial or conjoint) and cambium (open or closed).
3For stomata, name guard cells, shape and subsidiary cells.
4For leaves, state mesophyll type and stomatal distribution.
5Add one function per tissue.

Tissue Systems and Vascular Bundles in real life

The idea, met in an everyday situation. Answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Lawn grass in the sun

Suppose a lawn leaf rolls inward at noon in hot dry weather and flattens again by evening.

Which cells permit the rolling, in which type of leaf, and what is the advantage?

Try it first, then show the solutionSolution

Bulliform cells (large empty colourless cells) on the upper epidermis lose water and shrink.
This occurs in isobilateral monocot leaves such as grass.
Rolling reduces the exposed surface and cuts transpiration.

Answer: Bulliform cells roll the leaf and save water.

Memory hook: Bulliform = rolling cells.

Tricks to remember Tissue Systems and Vascular Bundles

Short memory aids. Say each one aloud once, then use it on a question the same day.

Endarch stem, exarch root
Protoxylem points to the pith in stems (endarch); to the periphery in roots (exarch).
Use it when: Xylem position
Open = Opens growth
Open bundles have cambium and can grow thicker.
Use it when: Bundle types
Bean dicot, Dumb-bell grass
Guard cell shapes.
Use it when: Stomata

Tissue Systems and Vascular Bundles: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Stomatal apparatus · 2 marks · Very short answerBoard level

Name the parts of the stomatal apparatus and the shape of guard cells in dicot and grass.

Try it first, then show the solutionSolution

Guard cells, subsidiary cells and the stomatal aperture (1 mark).
Bean-shaped in dicots, dumb-bell shaped in grasses (1 mark).

Answer: Guard + subsidiary + pore; bean versus dumb-bell.

Example 2: Bundle types · 2 marks · Very short answerBoard level

A coconut palm does not grow thicker with age but a mango tree does. Relate this to the type of vascular bundle in each.

Try it first, then show the solutionSolution

Mango (dicot) has open bundles with cambium that adds secondary tissue (1 mark).
Palm (monocot) has closed bundles without cambium, so no thickening by secondary growth (1 mark).

Answer: Open versus closed bundles.

Example 3: Tissue system identification · 3 marks · Short answerHarder board level

Name the tissue system to which each belongs: (a) cortex (b) root hair (c) cambium (d) mesophyll (e) pith.

Try it first, then show the solutionSolution

Cortex, pith, mesophyll: ground tissue system (1 mark).
Root hair: epidermal tissue system (1 mark).
Cambium: vascular tissue system (1 mark).

Answer: Ground, epidermal, vascular.

Example 4: Leaf comparison · 3 marks · Short answerHarder board level

A grass leaf curls in hot dry weather while a mango leaf does not. Name the cells responsible and contrast the mesophyll and stomatal distribution of the two leaves.

Try it first, then show the solutionSolution

Bulliform cells of the upper epidermis in grass lose water and roll the leaf (1 mark).
Mango: mesophyll is palisade plus spongy; grass: undifferentiated (1 mark).
Mango: stomata mostly on the lower surface; grass: on both surfaces (1 mark).

Answer: Bulliform cells; differentiated versus undifferentiated mesophyll; unequal versus equal stomata.

Example 5: Position of tissues · 5 marks · Long answerHOTS / competency

Suppose a section of a stem shows collateral open bundles in a ring. Identify the plant type, write the order of tissues from outside to inside in one bundle, explain why secondary growth is possible, and state the type of xylem.

Try it first, then show the solutionSolution

Dicot stem (1 mark).
Outside to inside: phloem, cambium, xylem (1 mark).
Cambium can divide to give secondary xylem and phloem (1 mark).
Protoxylem lies towards the pith: endarch (1 mark).
Ring arrangement shows the dicot (1 mark).

Answer: Dicot; phloem-cambium-xylem; endarch.

Where students lose marks in Tissue Systems and Vascular Bundles

The slips examiners see most often, and what to write instead.

Mistake: Cuticle in roots
Cuticle assumed for all epidermis.
Wrong working
Root epidermis has cuticle.
Right working
Cuticle is absent in roots; root hairs present.
Do this: Cuticle only aerial parts.
Usually costs: 1 mark.
Mistake: Endarch in roots
Positions reversed.
Wrong working
Root xylem is endarch.
Right working
Root xylem is exarch.
Do this: Roots are exarch.
Usually costs: 1 mark.
Mistake: Open for monocots
Stem types mixed.
Wrong working
Monocot stem has open bundles.
Right working
Monocot stem has closed bundles.
Do this: Dicot open; monocot closed.
Usually costs: 1 mark.

Exam tips

Name the guard cell shape for dicots and grasses.
Write both tissues and the example for open and closed bundles.
Use tissue-system lists in a table.
Draw labelled stomata if possible.

Practice questions on Tissue Systems and Vascular Bundles

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

Q1 · 1 mark · MCQBoard level
Dumb-bell shaped guard cells are found in
(a) dicots (b) grasses (c) gymnosperms (d) ferns
Hint
Monocot grasses.
Answer
(b).
Q2 · 1 mark · Assertion-reasonHarder board level
Assertion (A): Root vascular bundles are radial.
Reason (R): Xylem and phloem lie on different radii in a root.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Hint
Cambium decides.
Answer
(a).
Q3 · 2 marks · Very short answerHarder board level
What is the function of bulliform cells and where are they located?
Hint
Upper epidermis.
Answer
Large colourless cells in the upper epidermis of grass leaves; they lose water, shrink and roll the leaf, reducing water loss.
Q4 · 4 marks · Case-basedHarder board level
Read and answer.
Suppose a slide shows P: elongated cells with thin outer walls bearing a waxy layer; Q: parenchyma with chloroplasts below the epidermis; R: tissue conducting food.
(a) Name tissue systems of P, Q, R. (1)
(b) What is the waxy layer? (1)
(c) Name two cell types in R. (2)
Hint
Epidermal, ground, vascular.
Answer
(a) P epidermal; Q ground (mesophyll); R vascular (phloem). (b) Cuticle. (c) Sieve tube elements and companion cells (also phloem parenchyma and fibres).
Q5 · 3 marks · Short answerHOTS / competency
Suppose a plant keeps its stomata mostly on the upper surface because its leaves float on a pond. Explain why this differs from a typical land dicot and what might happen if it had stomata only below.
Hint
Floating leaves.
Answer
A land dicot has more stomata on the lower surface where loss of water is lower. A floating leaf has its lower surface touching water, so stomata on the upper surface let gas exchange occur. With stomata only below, they would be blocked by water and gas exchange would fail.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1.What are guard cells?Show answer
Cells that open and close stomata.
2.What are subsidiary cells?Show answer
Epidermal cells next to guard cells.
3.Cambium is present in which bundles?Show answer
Open bundles.
4.What is the ground tissue of leaves called?Show answer
Mesophyll.
5.What are trichomes?Show answer
Hairs on the epidermis.
6.Which position of protoxylem is endarch?Show answer
Towards the pith.

Tissue Systems and Vascular Bundles: frequently asked questions

What are the tissue systems?

Epidermal, ground and vascular.

What is a conjoint bundle?

A bundle with xylem and phloem on the same radius.

What is mesophyll?

The ground tissue of a leaf between the epidermises.

What are stomata for?

Gas exchange and transpiration.

What are bulliform cells?

Large epidermal cells that roll grass leaves.