dictyostele

A dictyostele is a type of stele, which is the central vascular cylinder found in plant stems and roots. In a dictyostele, the vascular tissues, xylem and phloem, are arranged in a ring with leaf gaps. What distinguishes a dictyostele is that the vascular tissue is broken up into numerous smaller strands, each surrounded by parenchyma. These individual vascular strands are separated by parenchyma tissues that represent the remnants of leaf gaps. This complex arrangement can be observed in the stems of many ferns and some other vascular plants.

The term dictyostele is derived from the Greek words "diktyon" meaning net, and "stele" meaning column. This name aptly describes the appearance of the vascular tissue, which resembles a net or lattice. The presence of numerous leaf gaps creates a highly dissected vascular cylinder. This structure is considered an advanced form of stele compared to simpler types like protosteles or siphonosteles. The evolutionary progression of steles often moves towards more complex and dissected forms, with dictyosteles representing a significant stage in this development.

The formation of a dictyostele involves the insertion of leaf gaps into a more continuous vascular cylinder. As leaves emerge from the stem, they create gaps in the vascular tissue. In a dictyostele, these gaps are numerous and overlap, leading to the fragmentation of the stele into multiple discrete vascular strands. Each strand contains xylem, typically located towards the center, and phloem, usually on the exterior. The parenchyma tissue fills the spaces between these vascular elements, contributing to the overall structure and supporting the vascular tissues.