Biology · Anatomy of Flowering Plants · NEET
| Location | Mesophyll cells: outer, spread through leaf | Bundle sheath cells: ring around each vein |
| First job | Fix CO2 into 4-carbon acid (OAA) | Release CO2 and run the Calvin cycle |
| Chloroplasts | Present, normal | Many, often larger, tightly packed |
| Seen in | All leaves | Well developed only in C4 plants (maize, sugarcane) |
Kranz anatomy is a leaf pattern found in C4 plants. Around every vascular bundle (vein) there is a ring of large, thick-walled cells called bundle sheath cells. The word Kranz means 'ring' or 'wreath' in German, so the name describes the ring shape. These bundle sheath cells are packed with chloroplasts and have no gaps between them.
Only C4 plants show Kranz anatomy. Common NEET examples are maize (corn), sugarcane, sorghum, and many tropical grasses. C3 plants like rice and wheat do NOT have well-developed Kranz anatomy. So if a question names maize or sugarcane and asks about leaf structure, think Kranz.
Mesophyll cells are the outer photosynthetic cells; in C4 plants they fix CO2 first into a 4-carbon acid (OAA). Bundle sheath cells form the ring around the vein; they receive the 4-carbon acid, release CO2, and run the Calvin cycle. Bundle sheath cells are larger, have thick walls, and contain many chloroplasts.
The bundle sheath cells act like a CO2 concentration chamber. The 4-carbon acid made in mesophyll cells is broken down inside the bundle sheath to give a high CO2 level. This high CO2 lets the enzyme RuBisCO work efficiently and reduces water loss and photorespiration. That is why bundle sheath chloroplasts are important.
The bundle sheath around vascular bundles is described in the Anatomy of Flowering Plants leaf section. The full C4 pathway and the name 'Kranz anatomy' are explained in the Photosynthesis in Higher Plants chapter. For NEET, link the two: the bundle sheath you see in leaf anatomy is the Kranz ring used in C4 photosynthesis.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Kranz is a German word meaning 'wreath' or 'ring'. It describes the ring of bundle sheath cells around each vascular bundle in C4 leaves.
No. C3 plants such as rice and wheat lack well-developed Kranz anatomy. Kranz anatomy is a defining feature of C4 plants like maize and sugarcane.
Yes. Bundle sheath cells are living parenchyma-like cells. In C4 plants they are large, thick-walled, tightly packed, and rich in chloroplasts.
NEET often links leaf anatomy with C4 photosynthesis. Knowing that the bundle sheath ring (Kranz) holds the Calvin cycle helps you avoid common trap questions about which cell does what.
