Plant tissue culture is something that I became interested in several months ago when an increasing number of conversations popped up in the houseplant community surrounding the Rhaphidophora tetrasperma. This plant has become extremely popular in the last year with prices skyrocketing to match its popularity.
Mid-way through the year, tissue-cultured specimens were introduced to the market at a much lower cost, making what was a very expensive plant readily available. I, too, saw these plants at my local greenhouse and picked one up for $25.
However, some people quickly noticed that there were differences between the tissue-cultured plants and the plants created through other methods of propagation. This sparked conversations about the quality of tissue-cultured Rhaphidophora tetraspermas including whether these plants were actually a different species altogether.
This post will dig further into what tissue culture is, why it is used, the quality of these plants, and more!
What is tissue culture?
Tissue culture is a method of producing new plants by taking a small portion of a mother plant’s cells and growing them out in a controlled environment.
The piece of a plant collected for tissue culture is referred to as an explant.
Explants are placed in a specific medium (often a gel, like agar) to induce growth. Then the medium is altered to encourage the explant to produce more shoots or plantlets. Finally, hormones are introduced to spur root growth so the plant can be transferred out of tissue culture.
Tissue culture is the first step of micropropagation.
Micropropagation is a method of producing a large number of plant clones in an efficient way.
When plantlets have grown roots in tissue culture, they are moved to soil (or sometimes vermiculite) to continue being propagated in a greenhouse for eventual sale.
The three main benefits of micropropagation are:By: Laknaa, https://pediaa.com/difference-between-micropropagation-and-tissue-culture/
1. Bulking up new plants – Micropropagation allows the production of a large number of clonal plants by means of tissue culture. Other vegetative propagation methods can generate only a few plants at a time.
2. Production of disease-free plants – Micropropagation uses the meristem, which cannot be infected by plant viruses in general. Typically, plant viruses spread through vascular tissue, which is not connected to the meristem.
3. Propagation of rare species – Micropropagation can be used in the propagation of rare and endangered plants as well as plants with difficulties in seed germination and seed dormancy.
Why do people use tissue culture?
Tissue culture (TC) is used for a number of reasons:
- TC allows a specific set of genetics to be passed on to plantlets; in other words, if healthy, robust plants are chosen as mother plants, then the plantlet clones should be healthy and robust as well
- TC can propagate rare plants at an unbeatable rate, giving growers a greater opportunity to meet demand
- TC allows growers to control the characteristics of a plant beyond health, such as variegation, leaf texture or shape, etc, which is normally unpredictable in traditional means of reproduction
Is tissue culture new?
Tissue culture has been around for a very long time (which was a surprise to me)! Gottlieb Haberland, an Austrian botanist, discovered the potential of a single cell to produce a plantlet, or the totipotentiality of a cell, in 1902. Through his discovery of totipotentiality, Haberland saw the potential of tissue culture.
The method of micropropagation, which uses plant tissue culture, has been around since the 1950s. Micropropagation was first utilized to produce orchids, which are challenging to produce through sexual reproduction.
Are plants propagated through tissue culture good or bad?
The answer to this question is largely subjective.
Tissue culture is successfully used to create plant stock for the agricultural, floral, and houseplant industry. The motivation and outcome of tissue culture is, by and large, to create better, healthier specimens. And often that is exactly what happens.
However, there are instances where the controlled environment used to propagate plants via tissue culture allows an unhealthy or undesirable plant that would have died outdoors to survive. In these circumstances, the weakened or undesirable plant may propagate and perhaps even proliferate, which is what some people argue has happened with the Rhaphidophora tetrasperma.
What is the current status of conversations surrounding the Rhaphidophora tetraspermas that have been tissue-cultured?
There have been 3 main discussions pertaining to tissue-cultured Rhaphidophora tetrasperma, all resulting primarily from the visual differences in the leaves of the tissue-cultured plant.
What differences did people notice?
The tissue-cultured Rhaphidophora tetrasperma had narrower, thinner leaves and sometimes had thicker stems with a smaller internodal distance (or distance between nodes).
This led people to wonder if the plant was actually a (1) different species, (2) a weak, less resilient version, or (3) just a plant that needed time to grow into its more well-known form.
Photos of all referenced plants in this section are at the end so you can examine and compare them for yourself.
Here’s an update on where each of these hypotheses currently is (as far as I can tell) amongst knowledgeable hobbyists.
1. Tissue-cultured R. tetraspermas might be something else entirely, like Rhaphidophora pertusa or a mature form of Epipremnum pinnatum ‘Cebu Blue’.
Multiple hobbyists noticed that the tissue-cultured version of Rhaphidophora tetrasperma resembled two other plant species:
Rhaphidophora pertusa: This species was seriously considered as the proper ID for the tissue-cultured R. tetrasperma due to its similar leaf shape and fenestrations (natural holes in leaves). However, aroid experts consulted with the detailed definition of this species and determined that the tissue-cultured R. tetrasperma did not meet those specifications.
Epipremnum pinnatum ‘Cebu Blue’: People also talked about whether it was possible that these tissue-cultured plants were actually mature versions of Cebu Blue pothos or Epipremnum pinnatum ‘Cebu Blue,’ whose leaves naturally develop fenestrations. Similarly to R. pertusa, hobbyists agreed that some of the characteristics used to identify Cebu Blue pothos were missing in the tissue-cultured R. tetrasperma.
Current status: These theories have been disproven. Tissue-cultured Rhaphidophora tetraspermas are R. tetraspermas, not another plant.
2. Tissue-cultured R. tetraspermas are a weaker, mutated version.
Some plant enthusiasts and hobbyists view R. tetraspermas grown via tissue culture as unhealthy and undesirable.
Tissue culture works by choosing a healthy, quality mother plant to clone, but the plantlets propagated from the mother plant are rarely grown in the exact same conditions as the mother plant. These environmental changes can alter the way a plant develops.
Additionally, companies can also use growth hormones to speed up the production of highly desirable plants, which can also change the growth habit and appearance of a plant until this hormone has worn off.
Lastly, there are instances in tissue culture where imperfections and irregularities can continue to thrive that wouldn’t have been able to survive in nature.
As a result, it is possible that tissue culture may produce less-than-perfect plants. However, it isn’t highly likely. Whether tissue-cultured R. tetrasperma is an example of a poorly propagated plant isn’t agreed upon within the community, largely due to the next hypothesis I think.
Current status: The community is divided. Some believe that the plant should be treated as a worthwhile R. tetrasperma. Some believe that the tissue-cultured plant is subpar and undesirable.
3. Tissue-cultured R. tetraspermas will eventually look exactly like the non-tissue cultured plants.
Since discussions about tissue culture and the R. tetrasperma began, there have been people documenting how their plants change and grow over time. There are now examples in forums and on social media of plants that exhibit tissue culture characteristics at one point and then grow into more natural characteristics at a later point in time.
This evidence has been enough for some people to believe that the tissue-cultured specimens are simply immature plants that need time to develop and grow. These hobbyists have embraced the tissue-cultured plant and are encouraging people to buy and grow them out, while others are not as quick to agree.
Meanwhile, another group finds both the tissue-cultured specimens (as they are) and the “regular” specimens worth growing and collecting regardless.
Current status: The community is divided here as well. Hobbyists either feel like the tissue-cultured specimens will never grow into the desirable version of R. tetrasperma or that these tissue-cultured plants just need time to mature.
My personal opinion:
I personally think it’s great that R. tetraspermas, tissue-cultured or not, are being offered at a lower cost. I find both plants attractive and own a tissue-cultured plant that I am interested to grow and observe over time.
I have a small non-tissue-cultured plant on order so I can assess for myself the differences between the two as I’ve never seen a non-tissue culture R. tetrasperma in person. I will update this post once that plant has arrived!
Update 3/21/2020: I received my non-tissue culture R. tetrasperma about a month ago. It arrived with some cold damage and I wasn’t sure how it would fair so I waited to update until I knew it would make it. Below you can see some side-by-sides of the tissue-cultured plant I own (the larger one) and the non-tissue-cultured plant (the little guy).
My personal assessment is that the leaf thickness and texture of both is about the same. Since the non-tissue-cultured plant is so small, it is possible that it will develop a more resilient leaf as it matures. The shape of the leaves is certainly different. The tissue-culture specimen’s leave is more elongated and lopsided. The non-tissue-culture specimen has a more rounded shape with slightly more even halves on either side of the main vein.
Tissue culture R.tetrasperma on the right; non-tissue-culture on the left
I’m holding the tissue-cultured plant’s leaf near the non-tissue-cultured plant (I knocked off a leaf by accident 🙁 )
Update as of 7/27/2020:
I’ve had my tissue-cultured R. tetrasperma for a year now. The plant is a very fast grower and was close to reaching my ceiling, even with lower light in a North-facing window. It hasn’t begun to grow leaves that look like the non-tissue-cultured R. tetrasperma. I’m starting to think it never will, but perhaps the next update will tell a different story!
Photos of all mentioned plants for comparison
Let’s take a look at another popular tissue-cultured plant: Monstera deliciosa ‘Thai Constellation’
Monstera deliciosa ‘Thai Constellation’ has been one of the most popular plants over the last year and remains one of the most popular plants. It’s unique variegation is made possible by having 2 different types of mutation.
One mutation creates the gorgeous star-like splashes across the leaves. The other mutation creates larger patches or sections of variegation.
Because this plant has two variegation mutations, it is easy to propagate through tissue culture. It is more difficult to lose both mutations in propagation than it is for plants that have only one mutation (like the other variegated Monsteras). Additionally, people haven’t cited (to my knowledge) any examples of M. deliciosa ‘Thai constellations’ that reverted to fully green leaves for the same reason.
Despite this, the science of variegation does show that it is possible for the plant to eventually lose both mutations. It is just a lot less likely. So if you want a plant that is highly likely to retain its variegation, this gorgeous plant might be the one for you!
The potential of tissue culture is greater accessibility to plants that are currently rare or expensive – which I love!
Tissue culture has allowed plants that were once rare or very slow to propagate to be produced much more quickly and consistently. Hobbyists, sellers, and growers are talking about many highly desirable plants being available within the next couple of years at a much lower cost through tissue culture, like the Philodendron ‘Pink Princess’, Monstera obliqua, other variegated Monsteras, and many more.
It is hard to deny the amazing potential of tissue culture within the houseplant industry both for buyers and sellers.
I look forward to the day that some of these expensive and beautiful plants become available to a wider audience. 🙂
Thank you so much to all of the hobbyists who contributed their thoughts, pictures, and time to help me create this post. I really appreciate you all. There wasn’t a single person that didn’t want to help when I asked. That is pretty special. Thanks again!
Note: I always want to get as many details right as I can. If you see something that isn’t quite right, please reach out and let me know!
Resources used for this article: