Cryptogams are classified as lower plants because they don’t have many of the structures we associate with plants. In part, this is because most cryptogams aren’t even in the plant kingdom! Complete this lesson to learn about this unique set of organisms.
What Is a Cryptogam?
The process of classifying living things into groups is called taxonomy, but sometimes it isn’t clear how each organism should be classified. The cryptogams are an example of a group that is impossible to squish into a single taxonomic category.As a group, cryptogams are ”lower plants” that use spores to reproduce. They don’t have the structures we normally associate with plants, like true stems, roots, leaves, flowers, or seeds, and their reproductive parts are hidden, so we call them ”plant-like” organisms. They share some characteristics with plants, yet they are still different enough to not fall into the same group as plants.
Okay, let’s take a step back for a moment and remember that all living organisms fall into three categories based on their cell type which we call domains, and within the domains are kingdoms of organisms. So, we have the Domain Bacteria, which has one kingdom called Eubacteria. Then we have the Domain Archaea, also with one kingdom, called Archaea. And last but not least, we have the Domain Eukarya, which has four kingdoms: Protista, Fungi, Plantae, and Animalia. We can further break these groups down into smaller and smaller categories, but domains and kingdoms are all you need to worry about right now.Despite sharing some characteristics with plants, only two groups of cryptogams are found within the Kingdom Plantae. In fact, members of the cryptogam group span four different biological kingdoms! Now you understand why cryptogams is a hard group to classify and describe; its members are pretty diverse.
Okay, let’s now take a look at the different types of organisms classified as cryptogams and where in our four kingdoms we may find them:
- Kingdom Eubacteria: Cyanobacteria (previously called blue-green algae)
- Kingdom Protista: Slime molds, green algae, other algal groups
- Kingdom Fungi: Basidiomycota mushrooms and their close relatives, Ascomycota cup fungi and their close relatives, and lichen
- Kingdom Plantae: Bryophytes (mosses, liverworts, and hornworts) and vascular cryptogams (ferns, horsetails, and club mosses)
Phew! That’s a lot of life forms with some strange names! Let’s now talk about three common characteristics of cryptogams.
Okay, so we’ve already learned that cryptogams don’t have the same structures as most plants, and that their reproductive parts are hidden. Well, some cryptogams only reproduce asexually, meaning they don’t need another organism to reproduce, through the use of spores. Still other types of cryptogams have generations that alternate between asexual reproduction and sexual reproduction, where male and female gametes from different organisms join together.
Cryptogams can live in aquatic environments, like algae, or on land; however, those that live on land do best in shaded or humid environments. Most cryptogams need a moist environment to survive. The ferns are the only cryptogams that contain a vascular system for transporting fluids within the organism, so the other groups need to have an external water source to function.
Many cryptogams are also microscopic in size – in fact, some of the organisms in the Kingdom Protista are only composed of a single cell! Some are also capable of photosynthesis, meaning they can make their own food. Organisms that can make their own food or energy are called autotrophs. Still other members of the cryptogams rely on outside sources for food just like we do. Some of these types directly absorb nutrients from other organisms, while some gain nutrients from dead organic matter.
As you can see, cryptogams are a diverse group of organisms, so it’s difficult to come up with a set of traits that applies to all members.
Importance of Cryptogams
Now that we’ve covered the classifications and main characteristics of cryptogams, let’s talk about the importance of cryptogams by introducing some fun facts about them. You might be surprised to learn that about 84% of all plant or plant-like organisms on Earth are cryptogams. In addition, algae alone are responsible for about half of all the photosynthesis that takes place, so don’t forget to thank them for your oxygen. And as if that weren’t enough, cryptogams also help build the earth’s soil.
They can create a layer that helps prevent erosion and traps moisture. The life cycle of cryptogams also provides nutrients like nitrogen to the soil, which enables other plants to grow.
Okay, let’s do some review to make sure everything we have learned sticks. Scientists try to classify living organisms into similar groups in a process called taxonomy, but some groups don’t have a clear place. Cryptogams are so-called plant-like organisms that share traits with plants, but most aren’t found within the Kingdom Plantae. Instead, they are found in the Domain Eubacteria and the Domain Eukarya and in the Kingdoms Plantae, Fungi, Eubacteria, and Protista, and they usually live in moist environments.
Some cryptogams are autotrophic, meaning they make their own food through photosynthesis, while others are heterotrophic, meaning they have to get food from other living organisms or dead organic matter. All cryptogams reproduce at least partly through the use of spores, meaning they can reproduce asexually, though some also do use sexual reproduction. Regardless of their specific characteristics, cryptogams play an important role in oxygen and soil production, making them a key part of the environment.