Transverse section of part of a young stem of a buttercup (Ranunculus sp.)
In a young dicot stem, such as this buttercup, the conducting tissue is contained within separate vascular bundles, forming a peripheral ring around the stem. In the centre of each bundle, the large lignified red cells are xylem vessels, responsible for the transport of water and mineral ions throughout the plant. Surrounding the vascular bundle is a cap of sclerenchyma, also stained red. This tissue also consists of lignified cells, but its function is solely one of support and not transport. Between the outer sclerenchyma and the xylem is a region containing the phloem, which transports sugars and other products of photosynthesis from the leaves to other parts of the plant.
The rest of this section mainly consists of large thin-walled parenchyma cells. These cells support the stem by their turgidity. In older stems the support role is achieved by growth of new tissues, in a process called secondary thickening.
The long axis diameter of a vascular bundle is about 320 µm.
Image by John Bebbington FRPS
Transverse section of part of a young stem of a buttercup (Ranunculus sp.)
In a young dicot stem, such as this buttercup, the conducting tissue is contained within separate vascular bundles, forming a peripheral ring around the stem. In the centre of each bundle, the large lignified red cells are xylem vessels, responsible for the transport of water and mineral ions throughout the plant. Surrounding the vascular bundle is a cap of sclerenchyma, also stained red. This tissue also consists of lignified cells, but its function is solely one of support and not transport. Between the outer sclerenchyma and the xylem is a region containing the phloem, which transports sugars and other products of photosynthesis from the leaves to other parts of the plant.
The rest of this section mainly consists of large thin-walled parenchyma cells. These cells support the stem by their turgidity. In older stems the support role is achieved by growth of new tissues, in a process called secondary thickening.
The long axis diameter of a vascular bundle is about 320 µm.
Image by John Bebbington FRPS