Question

Stelar system present in family Cucurbitaceae is
A. Siphonostele
B. Amphiphloic solenostele
C. Dictyostele
D. None of the above

Answer 1

In the vascular system of pteridophytes and higher plants, the vascular bundles are the basic unit in the stems and roots of the plants. Vascular systems are groups of complex, conducting tissues and are made up of more than one type of cell.

**Complete answer :** In a vascular plant, the central portion of the root or stem is known as stele. The stele contains tissues that are derived from the procambium. These include the vascular tissues and in some cases it may also include the ground tissue or the pith and a pericycle. The outer side of the stele lies the endodermis. The innermost cell layer of the cortex is called endodermis.
The stele can be defined as the central vascular cylinder which may or may not contain the pith and it is limited by the endodermis.
Steles are divided into protostele, siphonostele and solenostele types. In protostele type, the arrangement of the stele is of primitive nature. The vascular tissues consist of the central core of the xylem which is surrounded by strands of phloem in the protosteles. The protostele type is mostly present in plants like Lycopodium, Psilotum Gleichenia and some other varieties of ferns.
In type, the protostele condition is medullated. It is considered as a modification of the protostele conditions and such type of stele contains a tubular vascular region and a central parenchymatous region. A siphonostele is of two types, which are ectophloic type and amphiphloic type. In amphiphloic type of siphonostele type, the pith is surrounded by the vascular tissue. The inner phloem cylinder surrounds the central pith. The inner portion of the phloem is continued by the xylem which is in turn followed by the outer phloem.
The vascular tissue that forms a central cylinder around a pith with wide spaces of leaf gaps is known as solenostele arrangement. The arrangement in which it is broken up into a longitudinal arrangement of vascular strands around a central pith is known as dictyostele. But the stellar arrangement of Cucurbitaceae does not show any of the types of stellar arrangement.
> Hence, the correct and appropriate option is option D.

Note: The arrangement of vascular tissues in the central portion of the root and stem is called a stellar arrangement of various types including protostele, siphonostele and solenostele. However, these systems are not found in Cucurbitaceae