Question

Starch sheath is
(a)Endodermis of monocot stem
(b)Endodermis of dicot stem
(c)Petiole of a leaf
(d)Endodermis of monocot root

Answer 1

Hint: The innermost layer of the cortex is the starch sheath. It is the specialized cell to store starch like in a Pelargonium stem. They help in regulation of the movement of ions, water, and hormones into and out of the vascular system.

Complete answer:
The endodermis of dicot stem is Starch sheath. The endodermis is the central, innermost layer of the cortex and is the boundary between the cortex and the stele. It is composed of closely packed cells that have Casparian strips within their walls, water-impermeable deposits that regulate water and mineral uptake by the roots. It helps in the perception of gravity. It may also protect the plant against toxins moving into the vascular system.

Additional Information: -Stems of dicot plants have a well-defined epidermis with a cuticle, a layer of dermis along with multicellular stem hair. Examples are sunflower and Cucurbita.
-In a dicot stem, vascular bundles are arranged in a ring around the pith and the pith is concentrated at the core of the stem.
-Xylem is described as endarch and is used when there is more than one strand of primary xylem in a stem or root. The xylem develops from the inside towards the periphery, i.e., centrifugally. The protoxylem is closest to the center of the stem or root and the metaxylem closest to the periphery of the stem. The stems of dicot plants typically have endarch development and the roots are normally considered to have exarch development.
-The dicot plants have the cambium tissue which is a meristematic tissue and is present in the vascular bundles of the plant. This tissue has a regeneration capacity because of which it can form new tissue at the time of grafting.
-Closed vascular bundles are present in monocots as they lack cambium. Vascular bundles in monocot stems are closed, collateral, and endarch.
So, the correct answer is ‘Endodermis of dicot stem’.

Note: Vascular bundles are a part of the vascular transport system and are a collection of tube-like tissues that flow through plants, transporting critical substances to various parts of the plant. The vascular bundle consists of two forms: xylem and phloem.