Vascular bundle in dicot stem areA. Conjoint and collateralB. Conjoint and closedC. Conjoint, collateral and openD. Collateral and open

The correct answer is: C. Conjoint, collateral and open

In a dicot stem, the arrangement of vascular bundles is typically described as "conjoint, collateral, and open." Let's break down what these terms mean:

Conjoint: This refers to the arrangement of the xylem and phloem within the same vascular bundle. In a conjoint arrangement, both xylem (which carries water and minerals) and phloem (which carries nutrients and sugars) are present together within the same bundle.

Collateral: This refers to the positioning of xylem and phloem in the vascular bundle. In a collateral arrangement, the xylem and phloem are situated side by side, with xylem on one side and phloem on the other.

Open: An open vascular bundle is one where the vascular tissues (xylem and phloem) are not completely surrounded by a protective layer of cells. In contrast, a closed vascular bundle would be completely enclosed by specialized cells, such as those found in monocot stems.

So, in summary, the vascular bundles in dicot stems are described as "conjoint, collateral, and open," indicating the presence of both xylem and phloem in the same bundle, their side-by-side arrangement, and the lack of a complete protective layer around the bundle.