Question

The rhizome of ferns like the one shown in the previous question, have a dictyostele vascular cylinder. In your own words, what does this term mean and how does it differ from the protostele seen in the Lycophytes?

Answer 1

The stele is defined as a central vascular cylinder with or without pith surrounded by the endodermis. The leaves are connected with the stele by a vascular supply that runs from the leaf to the stele and it is known as the leaf supply.

Dictyostele: It is a type of siphonostele( in siphonostele pith is present and the vascular tissues are arranged in the form of a ring-like hollow cylinder). In dictyostele, large vertically elongated leaf gaps are seen. As a result, vascular tissues appear dissected and the resulting appearance is a net-like structure.

Protostele -the simplest form of stele and it is also the most primitive type. This stele doesn't possess a central pith and generally, xylem is surrounded by phloem but sometimes they may intermingle together. The difference between protostele and dictyostele is that the later possesses a central pith which is absent in the former one.

phloem -xylem Proto stele vascular bundle pith Dictyostele