Aquarium Plants: Understanding the Differences between Emersed and Submersed Grown Plants
If you're an aquarium hobbyist, chances are you've encountered the terms "emersed" and "submersed" when discussing aquatic plants. While the distinction may seem straightforward, the terminology used to describe these states of plant growth can be confusing. In this article, we'll clarify the differences between emersed and submersed grown plants, and explain how to identify them.
Emersed vs. Submersed Growth: What's the Difference?
In basic terms, emersed grown plants are grown out of water while submersed grown plants are grown underwater. However, the terminology used to describe these states of growth can vary depending on who you ask. Emersed plants are sometimes referred to as "emerged," while submersed plants may be called "immersed" or simply "submerged."
Identifying Emersed and Submersed Plants
Some aquarium plants look significantly different in their emersed form compared to their submersed form. Take, for example, Ludwigia Arcuata, Ludwigia Palustris, and Bacopa Monnieri. In the first image (left to right), these plants are shown in their emersed form, while the second image shows them in their submersed form. In this case, Bacopa Monnieri looks quite similar in both photos, but the two Ludwigia species look quite different. Emersed grown plants will generally have a 'waxy' coating whereas submersed grown plants do not.
Aside from appearance, there are other indicators of whether a plant is grown emersed or submersed.
If you are making a purchase online, a good seller will specify the form of their aquarium plants. However, in Australian pet/aquarium shops, you will typically see aquarium plants sold in two different ways. Either in tanks and under the water or in small round plastic containers.
Believe it or not, the plants in the tanks are not necessarily submersed grown. They are often purchased from a wholesaler in an emersed form and have been placed in tanks for sale purpose. Therefore they are likely to be in their emersed form but transitioning to submersed form. Sometimes these plants are submersed grown, but asking an employee of the store will be your best bet.
The plants sold in the small round tubs are called tissue culture plants. These plants are grown in sterile conditions and are guaranteed to be free from pests and algae. They are great for planting smaller aquariums, but can be expensive when bought in larger quantities. These plants are emersed grown.
Why Does it Matter?
Knowing what state your aquarium plants are grown in is important for three key reasons:
When purchasing plants that are grown in a submersed state, they can potentially carry pests such as snails, snail eggs, hydra and planaria. Snails are unsightly in large numbers but can help to clean algae and decaying matter. Planaria and Hydra, however, can be lethal to shrimps. Even if these plants have been sent in the mail, these pests will likely survive the journey and could thrive in your aquarium. If this is something that bothers you, we would recommend purchasing emersed grown plants as they are free from these pests.
Submersed grown plants may also have some algae. All aquariums have some form of algae, so plants that you receive in a submersed form will likely carry some form of it. As long as your aquarium is well balanced, this should not be an issue. However, if you receive a submersed grown aquarium plant with an immense amount of algae, this can throw off the balance of your aquarium. The newly introduced algae may outcompete your current plants for lights and nutrients and begin take over the tank. Therefore it is important to choose a reliable supplier of aquarium plants.
So why not just buy emersed grown plants? They are free from algae and snails and generally will ship better. The issue with emersed grown aquarium plants is that they have to transition back to their submersed state once placed in your aquarium. Depending on the plant species, this may be an easy or stressful transition.
During this process new, submersed leaves develop but old emersed leaves remain. These old leaves will not survive in the submersed state and will need to be removed once there is adequate submersed growth. If they are not removed they will decay and may trigger algae.
The transitioning process is much easier if you have an aquarium with rich aquasoil and Co2. Lacking these, you may struggle to keep your plants alive.
All considered, the best plant purchase for you will depend on your personal preferences and aquarium setup. A ‘high tech’, balanced aquarium with Co2 injection will generally make the transitioning process a breeze. The only drawback is that it will take longer for your plants to ‘take off’ and fill in your aquarium. If you’re running a basic aquarium setup and are unsure if you have the patience for plant conversion, then submersed grown may be right for you. Keep in mind that each plant will react to different conditions in different ways. Sometimes your own experimentation is the best way to find what is right for you.