What is the Difference Between Petiole and Pedicel

The main difference between petiole and pedicel is that petiole is the stalk of a leaf, attaching the blade to the stem, whereas pedicel is the stalk of an individual flower within a cluster of flowers known as an inflorescence. 

Petiole and pedicel are two types of stems present in plants, holding different structures. Stipules are the outgrowths appearing on each side of the petiole while peduncle is the main stem of the inflorescence, holding a group of pedicels.

Key Areas Covered

1. What is Petiole
     – Definition, Structure, Function
2. What is Pedicel
     – Definition, Structure, Function
3. What are the Similarities Between Petiole and Pedicel
     – Outline of Common Features
4. What is the Difference Between Petiole and Pedicel
    – Comparison of Key Differences

Key Terms

Inflorescence, Infructescence, Pedicel, Petiole, Stems

What is Petiole 

The petiole is the stem that attaches the leaf blade to the main stem. It arises at a node. The main function of the petiole is to conduct sucrose produced by the leaf by photosynthesis to the main stem and supply water and minerals to the leaf as required for photosynthesis. In addition, it provides structural support to the leaf. Some petioles consist of outgrowths in each side of them. They are known as stipules. Moreover, some petioles are very long as in rhubarb or celery. But, other leaves have short petioles. The leaves with a very short petiole are known as sub petiolate leaves. However, some leaves do not contain a petiole. They are known as sessile or apetiolate. 

Figure 1: The Leaf of Dog Rose with Stipules

For example, the leaves of the grasses are apetiolate, meaning they have no petioles. However, they form a pseudopetiole by narrowing the leaf blade at the bottom. Moreover, some leaves form phyllode by flattening and widening their petioles. Consequently, this type of leaves has reduced true leaves. Some phyllodes allow the plant to survive in stressful conditions. Additionally, in compound leaves, each leaflet is attached to a continuation of the petiole known as the rachis.  

What is Pedicel 

The pedicel is the stem that holds an individual flower in the inflorescence, which a cluster of flowers arranged on a stem, creating the main branch. Moreover, the stems of the infructescence are known as pedicels. Here, infructescence refers to an ensemble of fruits derived from the ovaries of the inflorescence. The sizes of both inflorescence and infructescence are the same. However, some flowers do not have a pedicel and they are known as sessile flowers.

Figure 2: The Inflorescence of Delphinium nuttallianum with Pedicels

Moreover, the stem that holds a group of pedicels is known as a peduncle. Interestingly, plant breeders try to optimize the size and the shape of the pedicel of pumpkins and other squash plants, which are used in Halloween, in order to produce the best “lid” for a “jack-o’-lantern“.  

Similarities Between Petiole and Pedicel 

• Petiole and pedicel are two types of stem in flowering plants. 
• Their main function is to attach the leaf or a flower to the main stem while providing structural support to the structure. 
• Furthermore, both arise at a node. 
• And, they contain conducting tissues of a plant such as xylem and phloem. 
• Moreover, they contain other plant tissues such as ground tissues. 
• Most of the times, they appear in green color. 

Difference Between Petiole and Pedicel 

Definition 

Petiole refers to the stalk that attaches the leaf blade to the stem while pedicel refers to the stem that attaches a single flower to the inflorescence. Thus, this is the main difference between petiole and pedicel.

Clusters 

Moreover, petiole does not occur in clusters while pedicel occurs in clusters. 

Structural Significance 

Besides, while stipules are the outgrowths appearing on each side of the petiole, peduncle is the main stem of the inflorescence, holding a group of pedicels. 

Functional Significance 

Furthermore, petiole is responsible for conducting the products of photosynthesis from leaves to the main stem of the plant while pedicel is responsible for conducting water and nutrients to the flower. Hence, this is the functional difference between petiole and pedicel.

Conclusion 

The petiole is the stem that attaches the leaf blade to the main stem. Some petioles contain stipules. The main function of the petiole is to conduct the products of photosynthesis to the main stem while providing structural support to the leaf. On the other hand, the pedicel is the stem which holds a single flower in the inflorescence, a cluster of flowers. Later, it becomes the stem of the infructescence as well. Moreover, it contains conducting tissues to supply water and nutrients to the flower and later, to the fruit. Therefore, the main difference between petiole and pedicel is the type of structure they hold and their function.  

References:

1. Lucas, Steve. “What Is a Stem? What Is a Petiole? Is the Support of a Leaf a Stem?” The Exotic Rainforest, Available Here.

Image Courtesy:

1. “Rosa canina blatt 2005.05.26 11.50.13” By Michael Becker (CC BY-SA 3.0) via Commons Wikimedia  
2. “Delphinium nuttallianum 15498” By Walter Siegmund (talk) – Own work (CC BY 2.5) via Commons Wikimedia