Secondary and Primary Growth in Plants
One of the main characteristics of living things is growth. Humans and animals will experience changes in height and weight as they age. Likewise, plants continue to grow. The difference is that plant growth only occurs in certain parts.
Plant growth can be influenced by internal and external factors, such as genetics, enzymes, hormones, temperature, sunlight, nutrients, and rainfall. There are two types of growth in plants, namely primary growth and secondary growth. Both types of growth are what make plants grow taller and bigger.
So, what is the difference between secondary and primary growth in plants? What is the process of secondary growth? Come on, see more in this article!
Definition of Growth
According to KBBI, growth is the state of growing, developing, advancing and so on. Although always associated with development, the two have different meanings.The term growth is used to describe visible changes. Examples include increasing plant height, increasing the number of leaves, the thickness of tree trunks, or increasing plant organs such as roots, branches, fruits, and flowers.
Meanwhile, plant development is used to describe changes that are not visible, but can be measured. Examples include embryo/seed development, cell changes, or enzyme development.
Plant growth and development starts from a sprout. The sprout then grows into a plant. After that, the plant forms fruits, seeds and flowers.
Secondary Growth in Plants
Secondary growth occurs due to the activity of lateral meristem tissues in the cambium in the trunk of dicotyledonous trees (two-lobed seeds). This happens because only dicotyledonous plants have a cambium.The cambium is a tissue that plays a major role in plant growth. There are 3 types of cambium that can be distinguished based on their function, namely:
- Secondary cambium (cork), found on the surface of the stem or root that has been broken. This cambium also causes the year circle on the stem.
- Intervascular cambium, serves to form pith fingers on plant vessels.
- Vascular cambium, functions to form xylem and phloem.
The older the plant, the bigger the stem. This happens because the cambium cells divide inwards to form xylem or wood, while dividing outwards to form phloem or bark.
However, cambium growth depends on the season. In the rainy season, water and nutrients are more available so cell division is faster. While in the dry season, the availability of water and nutrients decreases so that cell division decreases.
Quoted from the book Plant Physiology: An Introduction written by Fauziyah Harahap, the secondary growth process is as follows:
1. The Cambium Divides
First of all, the vascular cambium divides inward to form xylem and outward to form phloem. In this position the cambium is called intravascular.
2. Parenchyma Cells Change
Parenchyma cells found between the vessels (xylem and phloem) turn into intervascular cambium. The two cambiums will connect and form secondary xylem and secondary phloem.
3. Forming the Pith
The bigger the stem, the more gaps are needed to transport food. Therefore, pith fingers are made to transport nutrients throughout the plant body. The pith is a network of parenchyma cells that fill the gaps between the transport vessels.
The Difference Between Primary and Secondary Growth in Plants
Before discussing more about the differences between secondary and primary growth, it would be better if we first know the definition of primary growth.
Quoted from the paper Basics of Agronomy written by I Wayan Pasek Arimbawa, primary growth is the activity of apical meristem cells that cause stems and roots to grow lengthwise. This growth occurs due to meristem tissues found at the end of the stem and the end of the root.
The differences between primary and secondary growth include:
1. Meristem type
Primary growth occurs due to the activity of the apical meristem. This type of meristem is found at the tip of the roots and shoots of plants. Meanwhile, secondary growth occurs due to lateral meristems found in the vascular cambium.
2. Direction of Growth
Primary growth produces long shoots and roots. Meanwhile, secondary growth will increase the thickness of the plant stem.
3. Growth Sequence
Primary growth occurs at the beginning, starting from the plant is still in the form of an embryo. While secondary growth will follow primary growth.
4. Growth Time
Primary growth starts from the sprout until the tissue differentiation is complete. Meanwhile, secondary growth will begin when primary growth is complete.
5. Types of Plants
Any type of plant is bound to experience primary growth, as plants grow taller over time. However, secondary growth only occurs in dicotyledonous plants that have a cambium.
That's an explanation of the process and differences in secondary and primary growth in plants. Apparently, secondary growth does not occur in all plants. No wonder there are plants with small stems and some are large. Hopefully this information is useful, yes!
Quoted from the paper Basics of Agronomy written by I Wayan Pasek Arimbawa, primary growth is the activity of apical meristem cells that cause stems and roots to grow lengthwise. This growth occurs due to meristem tissues found at the end of the stem and the end of the root.
The differences between primary and secondary growth include:
1. Meristem type
Primary growth occurs due to the activity of the apical meristem. This type of meristem is found at the tip of the roots and shoots of plants. Meanwhile, secondary growth occurs due to lateral meristems found in the vascular cambium.
2. Direction of Growth
Primary growth produces long shoots and roots. Meanwhile, secondary growth will increase the thickness of the plant stem.
3. Growth Sequence
Primary growth occurs at the beginning, starting from the plant is still in the form of an embryo. While secondary growth will follow primary growth.
4. Growth Time
Primary growth starts from the sprout until the tissue differentiation is complete. Meanwhile, secondary growth will begin when primary growth is complete.
5. Types of Plants
Any type of plant is bound to experience primary growth, as plants grow taller over time. However, secondary growth only occurs in dicotyledonous plants that have a cambium.
That's an explanation of the process and differences in secondary and primary growth in plants. Apparently, secondary growth does not occur in all plants. No wonder there are plants with small stems and some are large. Hopefully this information is useful, yes!
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