Anomaly secondary growth in the Boerhaavia plant: A completely exhaustive study Plant growth is a complex phenomenon, both primary and secondary, whereas it deviates from the regular rules in some plants. One among interesting cases is the Anomalous Secondary Growth found in the Boerhaavia plant.In this article, an insight into the causes, processes, structural changes, and educational importance of this bizarre characteristic of plants will be given.
What is secondary growth?
In general, secondary growth in plants is the process through which their roots and stems increase in diameter.
This growth occurs mainly through two types of renal tissue:
- Vascular Cambium: which forms the xylem and phloem.
- Cork Cambium: which forms the outer protective layer (peridermis).
- conventional rules: and this is called abnormal secondary growth.
- This process is considered relatively normal in dicot plants.
Normal Secondary Growth vs. Abnormal Growth of Boerhaavia – Comparison
| Feature | Normal Secondary Growth | Anomalous Growth in Boerhaavia |
|---|---|---|
| Number of Cambium | Single Cambium | Multiple Cambial Rings |
| Position of Vascular Bundles | Arranged in a Ring | Scattered and Additional Bundles |
| Direction of Growth | Inward (Centripetal) | Outward (Centrifugal) |
| Interfascicular Cambium | Less Active | Highly Active |
| Academic Importance | Standard Practice | Unique Case Study |
What is Boerhaavia?
Boerhaavia is a herbaceous plant that mostly flourishes in tropical or subtropical areas. In India, it is popularly known as Punarnava and is considered as one of the most important plants in Ayurvedic medicine. Among botanists, it is especially popular because of its abnormal secondary growth in its stem.
How does abnormal secondary growth occur in Boerhaavia?
The abnormal growth seen in Boerhaavia is due to the parallel vascular bundles found in the internal structure of its stem. In normal dicot plants, the vascular bundles are arranged in a ring, but in Boerhaavia, this arrangement is polycentric.
Salient features:
- Multiple Cambial Rings: Boerhaavia develops more than one cambium ring, which alternately produce xylem and phloem.
- Activity of Interfascicular Cambium: Apart from the normal cambium, interfascicular cambium also becomes active, producing additional xylem and phloem.
- Formation of Accessory Vascular Bundles: Each new cambial ring can produce a new vascular bundle, giving rise to a characteristic structure in the stem.
- Centrifugal Growth: Most secondary growth occurs inwards in plants, but in Boerhaavia it is centrifugal i.e. outwards.
Stepwise process of secondary growth of Boerhaavia
- Initial primary structure: At the initial stage, the stem of Boerhaavia has normal primary xylem and phloem, which are not arranged in a ring form but are scattered.
- Initiation of cambial activity: The main cambium becomes active and starts forming secondary tissue in between the primary xylem and phloem.
- Development of subsidiary cambium rings: After some time, new cambial rings develop, which generate new xylem and phloem layers.
- Layer-by-layer structure: The layers of xylem and phloem generated from each new cambial ring give the stem a layer-by-layer jewel-like appearance.
Related Topics
- Mechanism of Normal Secondary Growth
- Role of Vascular Cambium
- Other Plants with Abnormal Growth Patterns: Achyranthes, Dracaena
- Case Studies in Plant Anatomy
Why does this abnormal process occur?
- This abnormal secondary growth in plants like Boerhaavia is considered to be an adaptive response that helps the plant survive adverse conditions such as drought, heat and poor soil.
- Its multiple cambial rings provide the plant with greater water-harvesting and nutrient transport capabilities.
Its Academic Importance in Botany
- The unique secondary growth found in Boerhaavia has become a special case study in botany.
- It is not only a great example of experimental study for students but also shows that nature can go beyond conventional rules.
- This topic is often a part of laboratory practicals and examinations at B.Sc. and M.Sc. level.
Conclusion
The unusual secondary growth found in the Boerhaavia plant teaches us how multifaceted and adaptive biological processes can be. It is an example that is not only instructive for students of botany but also provides us with an opportunity to understand the diversity of nature. While this unusual process is an area of research for scientists, it also demonstrates the amazing potential of biological evolution.
FAQs
Q1. What is anomalous secondary growth?
A. Anomalous secondary growth refers to any deviation from the normal pattern of secondary growth typically seen in dicot plants. It includes unusual cambial activity or vascular arrangement, as observed in Boerhaavia.
Q2. Why is Boerhaavia considered an example of anomalous secondary growth?
A. Boerhaavia exhibits multiple successive rings of vascular cambium and scattered vascular bundles, unlike the usual concentric arrangement, making its growth anomalous.
Q3. How does secondary growth in Boerhaavia differ from normal dicot plants?
A. In normal dicots, vascular bundles are arranged in a ring and have a single cambium. In Boerhaavia, there are additional cambia and accessory vascular bundles forming in successive rings.
Q4. What role does vascular cambium play in Boerhaavia’s growth?
A. Vascular cambium in Boerhaavia forms multiple concentric rings of secondary xylem and phloem, contributing to its thickening in an unusual pattern.
Q5. What are accessory vascular bundles?
A. These are additional vascular bundles formed between the primary ones during anomalous secondary growth, adding to the complexity of Boerhaavia’s stem anatomy.