Dracaena is a genus of succulent shrubs and trees. Many Dracaena species are used as houseplants as they can tolerate low light and can survive with only occasional watering. Here, let’s discuss the internal anatomy of the Dracaena stem in detail.
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Dracaena Stem Anatomy
Some Dracaena species contain a secondary thickening meristem in their trunk, known as dracaenoid thickening, that differs from the thickening meristem present in dicotyledonous plants. Only some monocotyledonous species exhibit this thickening. Here, let’s explore the normal anatomy and the anomalous secondary thickening of Dracaena.
Epidermal Zone
It has a single-layered parenchymatous epidermis that is replaced by periderm-containing cork cells. Phellem, also known as cork cells, are tightly packed and have thick walls. A few layers of thin-walled rectangular cells are found underneath this cork cambium or phellogen, which is organised in a storied way. Lenticels can also be found in the epidermal zone.
Cortical Zone
The cortex is multilayered and contains parenchymatous cells with enough intercellular space between them.
Ground Tissue
A sizable portion of the ground tissue is made up of parenchymatous tissue. Primary vascular bundles are spread throughout the ground tissue. Vascular bundles are circular, oval, leptocentric or amphivasal and are closed. It contains a phloem that is encircled by the xylem.
Explore: Preparation and Study of T.S. of Monocot and Dicot Roots and Stems
Anomalous Secondary Thickening
The secondary thickening pattern deviates certain monocots like Dracaena from the other typical plants. Dracaena shows a particular kind of secondary growth as a result of the cambial layer forming in the sub-epidermal area and also slightly outside the vascular bundles.
- Cambium is derived from the pericycle or deep layers of cortex.
- The fusiform or rectangle-shaped cambial cells continue to divide and form secondary tissues on the inner surface first and then form small amounts of tissues on the outside.
- External cambial cells are parenchymatous. The cells that are created inside the cambium are primarily vascular and somewhat parenchymatous in composition.
- The parenchymatous cells that the cambium produces internally, mature into lignified conjunctive tissue.
- Secondary vascular bundles are formed by the cells of the inner cambial ring.
- Typically, a single initial cell known as the vascular bundle-initial gives rise to the secondary vascular bundles. The initial cell of the vascular bundle divides twice through anticlinal division to produce two or three cells. Then, all of these cells undergo periclinal division to become peripheral cells.
- Finally, the mass of peripheral cells metamorphose into the xylem and the central cells transform into the phloem.
Keep exploring BYJU’S Biology to learn more such exciting topics.
See more:
- Monocot and Dicot Plants Anatomy
- Difference between Monocot and Dicot Stem
- Difference between Dicot and Monocot Root
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