Nonvascular Plants: Examples, Definition & Characteristics
This lesson will explore the world of a small and simple type of plant known as a nonvascular plant. The lesson will also discuss the types of nonvascular plants and their importance in the environment.
Introduction and Definition
How would you describe a plant? Most people would include some of the following terms in their description: green, tall, leaves, branches, stems, and flowers. Although this is what people commonly think of when they think of a plant, there are a group of plants, called nonvascular plants, which are very different from this common image of a plant.
Nonvascular plants are small, simple plants that are characterized mainly by their lack of a vascular system. Vascular plants, such as trees and flowering plants, have vascular vessels to transport water and food throughout the plant. Within vascular plants, the phloem is the vessel that transports food and the xylem transports water. Unlike vascular plants, nonvascular plants do not have a phloem or a xylem. Due to the lack of a vascular system, nonvascular plants are very small because they do not have the mechanisms required for transporting food and water far distances.
Another characteristic of nonvascular plants that sets them apart from vascular plants is that they lack roots. Instead of roots, nonvascular plants have rhizoids, which are small hairs that insert into the substrate to keep the plant in place. Vascular plants have roots not only for support but also to soak up water that is farther away from the plant. Due to the lack of roots in nonvascular plants, they are commonly found in moist environments so that they are always close to a water source and can absorb the water right into the main part of the plant.
Nonvascular plants also differ from vascular plants based on their reproductive strategies. Unlike some vascular plants that have complex reproductive strategies that include flowers and seeds, nonvascular plants have much more simple reproductive methods. Most nonvascular plants reproduce sexually by creating single-celled spores or asexually by vegetative propagation. Vegetative propagation is when part of the plant breaks off and develops into a new plant, with the exact same genetic information as the original plant.
Types of Nonvascular Plants
Nonvascular plants are also referred to as bryophytes and are divided into three different types, including mosses, liverworts, and hornworts.
Mosses are the nonvascular plants that are most commonly seen covering the forest floor or covering the trunks of trees. Most mosses have a short central stem with wiry branches and very small leaf-like structures. These bryophytes often look soft and cushiony or they can also resemble feathers. Mosses have the widest range of the bryophytes and can even survive in desert environments. Some mosses can survive complete dehydration and then rehydrate when water is available again.
Hornworts prefer very moist environments and some are even found submerged in ponds and lakes. This type of bryophyte has many thin branch-like structures and looks similar to soft pine needles. Hornworts that are submerged can grow larger than mosses and liverworts because the water provides them with support and structure.
Liverworts are often stated to be the simplest plant. They are commonly identified by flattened leaves and for many species the leaves grow in two distinctive rows. Due to their flattened leaves, liverworts grow very low to the ground and form large mats over the surface. They can be found in terrestrial or semiaquatic environments and are often referred to as weeds because they can easily take over farm land if the land is moist enough.
Importance of Nonvascular Plants
Although nonvascular plants are often overlooked during a hike due to their small size and location, they are actually very important to the environments they live in. There are some species of mosses that can absorb and hold up to seven times their weight in water. This ability to absorb water can be very beneficial because it helps maintain a moist environment. The water stored in the plant evaporates slowly and makes it possible for the environment to stay moist long after a rainfall.
Nonvascular plants can also be beneficial to the environment because of what they provide to the soil. Some nonvascular plants produce various nutrients that are passed to the soil and can be used by other plants. Also, nonvascular plants that cover a large surface area help maintain the cohesion of the land by reducing the risk of erosion.
Nonvascular plants are also very important to animals. Insects are known to use nonvascular plants for shelter. Many species of birds are also known to use nonvascular plants, especially mosses, as building material for their nests.
Although nonvascular plants are often thought of as simple or overlooked completely, they are in fact very interesting and unique plants. As long as they have a water source, they are able to survive on almost any kind of surface. They can also reproduce both sexually and asexually, which makes life as a small plant a little easier. Nonvascular plants are also very important to the environment they live in and the animals with which they share their environment.
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