Plants need light. To grow, plant use a process called photosynthesis. This process combines Carbon dioxide and water from the soil. To make the system work a plant requires energy from sunlight that is picked up by a green pigment on leaves called chlorophyll. After knowing this, it is hard to imagine any kind of plant able to grow inside a cave. But some can.
Caves are divided into sections or zones. The amount of light that reaches each zone is what determines the name. There are three zones, with each zone getting less light and one zone being completely dark.
The three zones are:
- Entrance Zone
- Dark Zone
- Twilight Zone
The entrance zone is as the name implies, the entrance to the cave. This section has the most activity in the form of wildlife and plant life. Upon entering the cave, one would notice that it has quite a bit of grass, trees, and plants leading into the cave since it has access to the most sunlight. There may even be some growing out from the rocks around the immediate entrance to the cave.
The second zone is the twilight zone. This part of the cave hosts low levels of sunlight. This section not ideal for plant growth has enough light to allow ferns, mosses, and other specialized species of plants can thrive.
Lastly, is the dark zone. The Dark zone location is at the very back of the cave. This part of the cave has no sunlight whatsoever. No plant could survive in this section of the cave.
Or can they?
The Dark Zone
Yes, some species can survive in this part of the cave. Fungi is one of the few species that thrive in this location because its moist, and this part of the cave is full of nutrient-rich bat guano, which makes a perfect soil for mushrooms. Algae would also fare down there. Algae do not need photosynthesis but can use different metabolic processes to produce their energy.
Some plants can grow in caves equipped with artificial light. Lampenflora is a species of plant that is like mosses, ferns, and algae. They tend to be less animated in color and somewhat flawed. Special measures need to be taken to control the growth of lampenflora. These invasive plants can disrupt a cave’s natural structure or any prehistoric writings that may be present. They can be controlled using chemical, physical, or biological methods.
As you venture further into a cave and as the light slowly diminishes, there is less likely a chance of finding any plant life. Some plants have evolved and adapted to these low-light conditions. Mosses and ferns are some of the plants that can thrive. One adaptation is the ability of all the plant’s chloroplasts (remember photosynthesis) to gather at the edge of the cell closest to the light source.
Nature is amazing.
There are approximately 8,000 different species of liverworts. Liverworts, along with hornworts and mosses, are considered bryophytes. Dating back over 4 million years, back to the Devonian Era, they are considered one of the earliest land-dwelling plants.
Liverworts are made up of just a few branching ribbons making it hard to differentiate between the root, stalk, or leaves. They lack any vascular systems, connective tissue, or stomata, which enables them to maintain its moisture. Liverworts can only survive in areas where it is extremely moist, dank, and low light environments.
There are over 12,000 species of ferns. Some species found will depend on the cave’s climate and the pH level of the soil. Some of the species that are found in caves are:
- Water horsetail (Equisetum fluviatile),
- Bird’s nest fern (Asplenium nidus),
- Brake fern (Pteris cretica)
- Ebony spleenwort (Asplenium platyneuron)
Ferns too lack the ability to reproduce through seeds, even though they have a vascular system. They rely on spores, which makes them ideal for moist environments like that found in a cave. Ferns use a two-generation complex process which is very sophisticated but still very successful.
Ferns have leaves called fronds that are photosynthetic. The fronds grow by the expanding or unrolling of a tight spiral called croziers (or fiddleheads). These fronds are high in nutrients, including protein, which makes them a vital resource for invertebrates and other forms of animal life that live in the cave.
There are about 12,000 species of mosses, and they are very closely related to the liverwort. The one difference is that mosses contain many rhizoids, a foot like structure that acts as an anchor for the plant, while the liverwort has only one rhizoid.
Mosses are void of seeds, flowers, and leaves, but they have long, spongy, and soft protuberances that house small amounts of chlorophyll that allow the process of photosynthesis to occur. Mosses are very vulnerable to dehydration, due to the lack of cuticles, a waxy substance that protects plants from dehydration. That is why an environment high in moisture and low in sunlight works.
Most species lack common names because all mosses look the same until they are dissected. But the ones that are names are the Orthotrichum truncate-dentatum, Ozobryum ogalalense, Pleurozium schreberi, Andreaea kilimandscharica, and Sphagnum russowii.