Insectivorous plants

• Insectivorous plants are plants that derive some or most of their nutrients by trapping and consuming animals, mainly insects.
• These plants are usually green so they can make their own food.
• However, the soil in which they grow is sometimes deficient in certain nutrients, especially nitrogen.
• Hence, these plants need to obtain these nutrients from outside sources.
• They are autotrophic but show heterotrophic nutrition as well, in order to supplement the deficiency of a particular mineral in the soil.
• These autotrophs supplement their nutritional requirements by trapping and digesting insects and other small animals.
• The trapped insects are killed and their proteins are digested by enzymes secreted by the epidermis of the leaf.
• They can live without insects but their growth is stimulated when they digest the insects.
• So, the leaves of these plants are modified in several ways for trapping insects.

Example:

• Some of the common examples are:

1. Pitcher plant
2. Drosera (sundew)
3. Bladderwort
4. Venus flytrap
5. Utricularia
6. Dionea

Pitcher Plant :

1. The leaf of the pitcher plant is modified to form a tubular pitcher-like structure.

2. The inside of the pitcher is lined with downward pointing hairs.
3. These hairs do not allow any insect to climb back up and escape.
4. Insects once trapped cannot escape due to the presence of numerous downward pointing hairs in the pitcher.
5. The fluid at the bottom of the pitcher contains digestive juices that digest the insect.
6. Among the carnivorous plants the biggest, and the most amazing, are the vines known as the tropical pitcher plants.
7. They have been known to capture and eat not only insects but also frogs and rarely even rodents.

Venus Flytrap:

• The trap of the Venus flytrap is a highly modified leaf.

• On the inner surface (reddish surface to attract insects) there are short, stiff hairs.

• When anything touches these hairs, the two lobes of the leaves snap shut in less than a second.

Drosera (Sundew):

1. The leaves of sundew have tentacles with drops of a sticky substance called mucilage at the ends.

2. The insects get stuck in this substance and become entangled.
3. The helpless insect then gets digested.

Bladderwort:

• The slender leaves of bladderworts bear a large number of very small, pear-shaped bladders.

• This opens a trapdoor and the prey is sucked in within one-thousandth of a second.

Symbiotic Plants:

• There are certain plants which live in association with other species and share their food resources.
• Both the types mutually gain from each other.
• Such plants are called symbiotic plants and the relationship is called symbiosis.

Example:

• Lichens are an association between a fungus and a microscopic plant — green algae.
• The fungus obtains nutrients from the algae, and the fungus in turn provides shelter to the algae, so that it can grow in harsh conditions like rock surfaces where it would otherwise not survive.

Peas containing bacteria–Rhizobium:

• Roots of certain plants such as peas contain bacteria called Rhizobium.

• Rhizobium converts atmospheric nitrogen into plant-usable forms, e.g., ammonia.

Mycorrhizae:

• Fungi and the roots of almost all vascular plants form mutualistic associations called mycorrhizae (singular, mycorrhiza).