Introduction

The pitcher plant belongs to the genus Nepenthes. This plant is carnivorous in nature as it attracts and traps invertebrate prey using nectar-secreting pitchers. Thus pitcher plants come under carnivorous plants sometimes called insectivorous plants. So let us discover what is a pitcher plant and how it traps insects.

Why some plants are carnivorous or insectivorous?

There are approximately 600 species of carnivorous plants that come under 6 different angiosperm subclasses including both monocots and dicots. Many carnivorous plants have developed a unique way to catch their prey.

Some species of plants developed a carnivory nature in the course of evolution representing an adaptation to nutrient-poor soil (1). In order to fulfill their nitrogen and other nutrient requirement for nutrition, these plants adapt themselves to carnivorous or insectivorous plants.

What is a pitcher plant?

Pitcher plants are carnivorous or insectivorous plants that grow in nitrogen-deficient soil.  Therefore, they developed a special trap to catch prey like different types of insects and fill the deficiency of nitrogenous protein in their body. They trap insects as food so they are often called insectivorous. The leaves of this plant look like pitchers. Bigger pitcher plants sometimes hunt rats or frogs. Pitcher plants are a variety of carnivorous plants whose modified leaves act as a kind of danger trap (3) & (4).

The pitcher plant has hollow special types of leaves. This leaf looks like a jug or pitcher. The leaves which look like pitchers are used as traps for prey. These plants are called pitcher plants because of their structure and shape. The scientific name of the pitcher plant is Nepenthes (2).

Geological distribution

These plants are found in different parts of the world like South America, Malaysia, Madagascar, India, and Sri Lanka. Pitcher plants belong to the Nepenthaceae and Sarraceniaceae families. Nepenthaceae consists of a single genus, which is called nepenthes. There are more than 100 pitcher plant species in this genus. One of these species is the American pitcher plant. These plants are mainly found in the tropical region (6).

Characteristics of a Pitcher plant

• Pitcher plants are very colorful and shiny.
• The plants of this species have a great odor and flavor, which attracts insects.
• All these plants are deficient in nitrogenous proteins.
• These plants mainly feed on insects therefore known as insectivorous.
• All of these plants create a special kind of trap and prey on insects.
• They get nourishment by eating various insects and even rats, frogs, etc., and develop their bodies.
• Pitcher plants catch insects by pitfall traps.
• Pitcher plants can survive from a few weeks to 9 months, depending on the species and possibly environmental factors.
• These plants secrete a special type of enzyme from their bodies to catch insects.
• At present, there are more than 80 types of pitcher plants in the world.
• The pitcher plant is apex pitcher-shaped and brightly colored. When the insects sit on the apex of the leaf, they slip and fall into the liquid inside the pitcher. The insect digests the liquid inside the pitcher and gets the plant nutrients (3) & (6).

Why are the pitcher plants included in the carnivorous class?

Photosynthesis is one of the most important parts to survive on this planet. For this, all plants absorb water and minerals from the soil. These elements combine with carbon dioxide to prepare the food in the presence of the sun. Nitrogen is one of the primary elements for plant growth. So most plants grow best in nitrogen-rich soils.

But pitcher plants grow in wet and damp swamps where the nitrogen content is very low. To fulfill the requirement of nitrogen, pitcher plants trap different animals or insects.

These plants collect minerals from their carcasses after they die. The leaves of pitcher plants especially help them in this task. They kill animals and collect nutrients from their carcasses, so they belong to carnivorous species (5) & (6).

Structure of a Pitcher plant

The pitcher plant has both ordinary leaves and brightly colored pitcher-like leaves. The evolution of a pitcher-like structure is formed by the infolding of the leaf with the upper surface becoming the inside of the pitcher and the lid of the pitcher. In some pitcher plants, the lid acts as an ornament on the edge of the pitcher. The leaves of different species of pitcher plants may vary in size, color, and shape. They can range in length from just 2 inches (5 cm) to 2 feet (60 cm) (3).

Pitcher plant’s hunting method

The mode of hunting in all the pitcher plants is almost the same. They prey on pitfall trap methods. There are some small pitcher plants that prey on flies, beetles, ants, and other insects. Whereas large pitcher plants prey on small frogs or rats.

They catch prey without any movement. The structure of the pitcher plant is such that it acts as a prison for insects to enter inside it. The leaf attached to the pitcher acts as a long tube. At the head of the tube is a colorful entrance with a cup-shaped bottom.

Rainwater accumulates in the pitcher plants that grow near the soil. The cover of most pitcher plants prevents large amounts of rainwater from entering through the entrance. The lid is always open. A special type of enzyme is secreted at the entrance of the pitcher which attracts the insects. The inner wall of the tube is as smooth and slippery as ice. As a result, the insect slipped and fell towards the bottom of the tube.

There are countless antennae at the bottom of the tube. After crossing these, if the insect falls down, it is no longer possible for it to climb upwards. At one point it sank into the bottom of the water. The digestive enzymes then come out from under the pitcher.

The plant absorbs and digests the soft parts of the insects and the hard parts get deposited at the bottom of the pitcher. In this way, the pitcher plants prey on and nourish themselves (4) & (6).

Importance of pitcher plant

Pitcher plants then release enzymes from their bodies to digest the insects and take nitrogen from their bodies. This nitrogen is an essential element for the growth and development of plants. So they take nitrogen to grow and develop their body and get nutrition.

When these plants die, they are decomposed by various insects and return their body’s nitrogen to the environment. Thus pitcher plants play an important role in maintaining nitrogen balance in the environment (3) & (5).