Thorns and Spines
It is difficult to spot the difference between thorns and spines based only on their appearance since they both look almost identical. To know what is the difference between thorns and spines, we must look at how these two are created from different parts of a plant. While the thorn is a modified stem, the spine is a modified leaf. At Vedantu, we have created a comprehensive summary of spines, thorns, and pickles along with their differences.
Spines
Spines are sharp, pointed structures on a plant and are modified leaves. They protect the plant from predators. An example of spines can be seen in the Opuntia plant where the minute leaves of axillary buds transform into spines. Another example is pineapple where the margin of leaves is modified into spines.
Thorns
Thorns are woody, pointed structures in a plant that protect the plant and help in climbing. They are modified axillary leaves and are different from both spines and prickles. Thorns may be branched or unbranched and are always subtended by a leaf.
What is the Difference between Thorns and Pickles?
Spines are structures that are sharp in nature and are pointed. They are part of the plant and are modified leaves. These provide protection of the plants from predators. An example of spines is observed in the Opuntia plant where the leaves or buds of the axillary transform into spines. Another example of such plants is pineapples which have the margin of their leaves modified into spines. Spines are thus modified leaves or stipules which are parts of the leaves and have extensions of the leaf veins. The spines have vascular tissues. They are also called petiolar spines or leaflet spines and even stipular spines which are examples of spines that develop as a leaf part that has midrib, petiole, and secondary veins. Spines are observed widely in the family of cactus. The cacti have a particular kind of spine that is of different origin and are called glochids. The glochids are small and deciduous with many retrorse barbs along the length of the plant. Thorns on the other hand are woody and pointed structures that protect the plant and also help them in climbing other surfaces. They are axillary leaves that are modified and they differ from prickles and spines. The thorns are either branched or not branched.
The terms prickles and thorns are often mixed and used interchangeably but there is a slight difference between thorns and prickles.
While thorns are formed from internal tissue (endogenous), prickles develop from external tissue ( exogenous).
Prickles develop from the epidermis and cortex of plant stems while thorns are modified branches.
Prickles can also occur on leaves and protrude from the main veins of the leaf unlike thorns
Prickles can also be seen on adventitious roots and some fruits unlike thorns
An example of prickles is the rose plant.
Spines, thorns, and prickles all prevent the animals from eating the plant.
Let’s look at the difference between thorns and spines in detail.
FAQs on Difference Between Thorns and Spines
1. What is the Main Function of the Spines of a Plant?
The primary function of spines is to protect the plant. During hot weather or dry conditions, spines prevent water loss from the plant. When the leaves are modified into spines, their surface area reduces and this lessens the water loss. Photosynthesis in this case is performed by the stem.
2. What is the Main Difference Between Spines, Thorns, and Prickles?
The main difference between spines, thorns, and prickles is:
Thorns are modified stems of a plant
Spines are modified leaf or stipule
Prickles are an outgrowth from the epidermis of the plant
3. Does the Cactus Plant Have Thorns, Prickles, or Spines?
Most cactus species do not have leaves and are covered with spines that are modified leaves. These spines grow from structures called areoles. They help the plant in conserving water as well as defending against herbivores. The spines on a cactus help in preventing water loss by reducing the airflow close to the plant and giving it some shade.
4. What is the difference between thorns and spines?
The spines are part of the leaves which are modified whereas the thorns are branches that are modified. The spines are placed at the same place as leaves. On the other hand, the thorns develop in the axis of the bud and are seen in the plant node. The spines may be connected to the vascular tissue but the thorns aren’t connected to the vascular tissues. The main function of the spine is to protect the plant and in the prevention of excess loss of water. The thorns provide protection to the plant and also help in climbing. The spines are formed exogenously by external tissue. On the other hand, thorns are formed by internal tissues endogenously.
5. What are prickles?
Prickles can be defined as woody and pointed outgrowth from the plant’s epidermis. It has various functions. For example, the Gunnera plant keeps protection. In roses and brambles, prickles help these to remain hooked to support. Prickles are modified by a trichome which is multicellular. Prickles can be compared to hair but they are comparatively very coarse like we observe in roses. Prickles are extensions of the epidermis and cortex. Examples of plants that have prickles are roses.
6. What are the functions of thorns, prickles, and spines?
The functions of thorns, pickles, and spines are mostly due to mechanical development. Rather than chemical defenses, they are called physical or mechanical defenses and they provide protection to the plant.
These structures protect the plants from the herbivores who feed on them. In many plants, spines help in controlling the excess loss of water. They have been found to insulate the plants and provide them protection from harsh temperatures and conditions. In the Saguaro cactus, the spines give shade to the apical meristem in summer. Similarly, in Opuntioideae members, the glochids give insulation to the apical meristem during winters.
7. What is the difference between thorns and prickles?
The difference between thorns and prickles are as follows:
Thorns grow endogenously, which are formed by internal tissues. The prickles, on the other hand, develop from external tissues or develop exogenously.
Thorns are modified branches whereas the prickles develop from the cortex and epidermis of the stem of plants.
Unlike thorns, prickles may develop on leaves and protrude from the main veins.
Unlike thorns, prickles are also observed on adventitious roots and some fruits too.
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