Biology · Anatomy of Flowering Plants · NEET
Intrafascicular (also called fascicular) cambium is the cambium already present INSIDE the vascular bundle, between the xylem and phloem. It is a primary (pre-existing) tissue. Interfascicular cambium is NEW cambium that forms LATER between the bundles, from medullary ray cells. Trick: INTRA = inside the bundle, INTER = in the gap between bundles.
It arises from the medullary ray cells (also called pith ray parenchyma) that lie in the region between two vascular bundles. These parenchyma cells become meristematic again (they start dividing) and turn into cambium. Do NOT confuse this with the dicot ROOT, where vascular cambium comes from conjunctive tissue and pericycle.
Step 1: the intrafascicular cambium is already present inside each bundle. Step 2: the medullary ray cells between the bundles become active and form interfascicular cambium. Step 3: the interfascicular cambium joins the intrafascicular cambium on both sides. Now there is one continuous cambium in a ring shape, called the cambial ring. This ring then cuts secondary xylem inside and secondary phloem outside.
It is a secondary meristem (secondary in origin), because it forms later from permanent parenchyma cells that become meristematic again. But note: in NEET, both fascicular and interfascicular cambium are classified as LATERAL meristems because they cause growth in girth. This exact point was asked in NEET 2023.
In a dicot stem the vascular bundles are open (cambium is present) and arranged in a ring, so the gaps between them can be bridged by interfascicular cambium to make a full ring. In a monocot stem the bundles are closed (no cambium) and scattered, so no cambial ring forms and there is no normal secondary growth.
Consider the following plant tissues. Identify the lateral meristems among the above. (A) Axillary buds (B) Fascicular vascular cambium (C) Interfascicular cambium (D) Cork cambium (E) Intercalary meristem. Choose the correct answer:
Try the real previous-year questions from this chapter — each with the answer and a full solution.
From medullary ray (pith ray) parenchyma cells lying between two vascular bundles. They become meristematic and turn into cambium.
A continuous ring of cambium formed when the interfascicular cambium joins the intrafascicular cambium of all bundles. It is the tissue that carries out secondary growth in a dicot stem.
No. Monocot stems have closed, scattered bundles with no cambium, so no interfascicular cambium and no normal cambial ring form.
Yes. Fascicular cambium and intrafascicular cambium mean the same thing: the cambium already present inside each vascular bundle.
It cuts off secondary xylem towards the inside (centre) and secondary phloem towards the outside, increasing the girth of the stem.
