Question

Explain the types of conjoint vascular bundle.

Answer 1

When xylem and phloem of a vascular bundle lie on the same radius, it is called the conjoint vascular bundle. It is an arrangement of how the xylem and phloem are arranged.

Complete Answer:
The conjoint vascular bundle, are of two types,
(1) Collateral
(2) Bi-collateral
(1) Collateral- The collateral is the type of conjoint vascular bundle. In this, the xylem is arranged towards the interior and the phloem arranged towards the exterior. The xylem and phloem are arranged side by side in the same radius.

In the collateral vascular bundle, only one patch of xylem and one patch of phloem are present. This may be either open or closed.
The conjoint collateral vascular bundle has two types. On the basis of cambium,
(a) Open
(b) Closed
(a) Open- In this, the xylem is towards the inner side and the phloem is towards the outer side.
Cambium is present between xylem and phloem.
(b) Closed- In this, xylem towards the inner side and phloem towards the outer side and there is no cambium between them.

(2) Bi-collateral- In Bi-collateral vascular bundle, xylem is placed in the middle and there are two patches of phloem and cambium tissue at each side.
These types of vascular bundles are found in plants of members of the family, cucurbitaceae, Solanaceae, Convolvulaceae.

Note: Vascular tissues containing xylem and phloem are organized into discrete strands called vascular bundles. The main function of xylem is to transport water and minerals from roots to different parts of the plant body. The function of phloem is to transport food to the parts of the body.