We get a lot of questions about what exactly it means for a plant to be a cultivar or a variety, and if that is “good” or “bad” for pollinators or ecological value. There are are a lot of strong opinions on the matter, but to really answer that question it is important to know how that plant is produced, where it was discovered, and what, in terms of flower form and leaf color, has been altered. It can be very confusing! Come along with us on our blog series where we plunge into the intrigues of plant reproduction and patenting, and the impact that the horticulture industry has on the market for native species.
Today’s question is: What does it mean when a cultivar or variety is “clonal”? And what are the pros and cons of using them in the landscape?
People often think a “clone” is a newfangled science fiction concept. But some plants reproduce this way naturally. Take the beloved house plant Chlorophytum comosum, also known as spider plant or airplane plant.
Anyone who has owned one of these beauties knows how prolifically it produces miniature versions of itself. In nature, these babies would eventually drop off and land in the crevice of a tree or log to put down roots and make more miniature versions. The mother plant lives on seemingly forever! We see the same method of reproduction in rhizomatous plants like sumac, persimmon and aspen trees. The shoots that form vast colonies are all connected, all part of one organism. We call these clones because, genetically speaking, they are just copies of their parent. As there was no sexual reproduction to produce a seed, the parent plant and baby plant are identical.
Clonal Propagation
Humans often help the process along if we want to preserve the attributes of a particular plant. Clonal propagation can be vegetative, via tissue culture, or by division. Let’s say I’m out on a hike when I spot a clump of little bluestem that catches my eye. Very unique: short and reddish, more rounded, compact and deeply colored than the taller thin bluestem all around it. This plant may be a genetic outlier, holding a mutation in its genome that caused these characteristics. With the permission of the landowner, I could dig up a part of the plant and take it home. That is known as a division. It creates a duplicate of parent plant, with the same genetic makeup. And if I were to grow it in my yard and divide it a hundred more times, it would still be like the original.
True Blue
If I plant this bluestem in my garden, it should show the same physical traits as the parent plant. I say should because this is the test – field trials are necessary to make sure that a division (clone) of a desired plant actually holds true. Sometimes mutations are flukes, a product of some environmental factor like predation or soil conditions. In that case, the desirable traits do not stay over time. If I manage to keep it alive for several seasons, and it continues to look as expected, then we are really in business! If I went on to field trial it many many times, name it, and market it to garden centers, this would end up being a new cultivated variety, or cultivar. Not to be confused with a botanical variety.
Why not just collect seeds instead?
In many cases, seed from the plant we want to reproduce does not come true to type. This means the special qualities we liked in that particular plant are not transmitted to the offspring reliably. Seeds are produced via sexual reproduction and gene mixing. The natural process of pollination creates a sort of genetic smoothie – everything gets all mixed together to create new individuals, with its variable characteristics. Some will be tall, short, upright, floppy, more reddish or almost completely blue. If you want the exact look as the original plant you discovered, reproducing clonally is necessary.
Pros and Cons of Clonal Propagation
The benefit of clonal propagation is uniformity. Mass planting in urban settings often demands certainty from height, color, habit and vigor. Using seed-grown bluestem gives more variable results. I advise folks to think carefully about their goal when planting natives: Is it to create a prairie reconstruction or research plot? Seed strains and straight species are best here, as they will give you the most natural results, and hopefully add to the genetic fitness of all the nearby bluestem species. Do you need something very tidy and reliable for an HOA, city street median, or parking lot island? Cultivars will likely yield more uniform results, and be well received by the audience you are trying to impress. The plants you use truly depend on the goal you are chasing and the maintenance plan you have in place.
Later in this series, we will dive into the complicated process of plant patenting and the complicated language around varieties and hybrids. Stay tuned!