Tag Archives: cultivar

A League of Their Clone

Posted on by Katie Schmidt

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.

Photo via Wikimedia Commons http://Florian Wickern, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

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.

‘Twilight Zone’ Bluestem, photo courtesy of Walter’s Gardens.

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.

This chart made by Hoffman Nursery (one of our grass suppliers) shows the wide variety of traits that little bluestem can have, and the cultivars that reliably exhibit them. Named cultivars are the result of many field trials and much data collection before they eventually come to market as trusted landscaping specimens.

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.

Two prairie dropseed plants (straight species, non-clonal) seen here, planted at the same time just a few feet apart. They exhibited wildly different growth rates. In the foreground, it is only twelve inches tall while nearby a different individual grows to be almost three feet! Some of this difference is likely genetic variation.
‘Tara’ is a dwarf dropseed cultivar well-suited for public spaces because of its short and upright habit. It was found growing in Southeastern Wisconsin by plantsman Roy Diblik. Photo from Hoffman Nursery, originally from Intrinsic Perennials.

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!

Native Plants in Modern Horticulture: Terminology

Posted on by Katie Schmidt

We get a lot of questions about what exactly it means for a native plant to be a cultivar or a variety, and how that might affect pollinator attraction or ecological value. The short answer is: it’s complicated! To really understand the conversation happening around nativars, it is important to understand how they come to exist. How is that plant reproduced? Where it was discovered? What does the patent says about its parentage? It can be a tricky road full of complicated terminology, and we will be posting a series of blogs to dig into this topic, and how it applies to the native plants common in the Arboretum and at our FloraKansas fundraiser events.

Button bush (Cephalanthus occidentalis) is a native shrub growing up to 12 feet tall. The variety ‘Sugar Shack’ is a much more manageable size at 6 feet tall and wide. Varieties created by the horticulture industry can be helpful in adapting these beautiful plants to fit urban spaces, but their benefit to the ecosystem is still being studied.

The first post in this series is a primer on terminology used in these discussions. Future posts will cover naturally occurring varieties versus cultivars, hybridization and breeding programs, and what it all means for native plant enthusiasts!

The Language of Plants

Cultivar, hybrid, variety — these terms are often tossed around willy nilly and their definitions get mixed up. This article does a fantastic job of explaining it in lay terms, but the even shorter version is:

  • Variety = naturally occurring genetic variation within a plant species. Seed is usually true to parent plant.
  • Cultivar = variation within a plant species developed through human intervention; seed usually is not true to parent plant.
  • Hybrid = product of a cross between two different species or varieties, which can occur naturally or by human intervention. Seed may be sterile, or may be viable, and may or may not grow to reflect the parent plants.

A naturally occurring variety may later be found to be the product of spontaneous hybridization. A hybrid plant may have been created with two cultivars as parent species. These descriptors are not always mutually exclusive, and can overlap in confusing ways!

If you search for ‘Hello Yellow Milkweed’ online, you get a lot of results that call this a cultivar or even a hybrid. But I can’t seem to find any plant patent or breeding information yet. So, this may be a situation where the terminology being used is incorrect and it might be just a naturally occurring color variation. I will keep searching for info!

These simple definitions from the American Begonia Society are also helpful:

A SPECIES is a natural grouping of similar plants that can interbreed and reproduce by seed.

A NATURAL HYBRID occurs between two different species.

A VARIETY appears naturally within a species, but it has some distinctive trait which sets it apart.

Just to Muddy the Waters…

‘Variety’ is different than ‘Plant Variety’. As frustratingly similar as those terms are, the first is a taxonimical distinction, while the second is a horticultural industry term. For example, Baptisia australis var. minor is a natural variation on Baptisia australis. It is shorter and more compact than the regular species. This is a botanical or taxononmical variety, and you can tell by the way it is written. But a Plant Variety is usually listed ‘like this’, and describes a patented cultivar. This distinction protects the plant breeders rights. Echinacea ‘Summersong FireFinch’ (listed as Echinacea purpurea G0052Y under its patent) is an example. Too often even the plant producers and sellers do not use the terms uniformly. I have seen Baptisia australis var. minor tagged as Baptisia ‘Minor’, which may cause people to think it is a patented or man-made variety, when it is not.

All that to say, it is very difficult to know what you are getting sometimes! Check out our other posts diving into detail on hybrids and cultivars to get a better understanding of what to look for when purchasing.

‘Julia’ is a hybrid coneflower sporting vibrant orange flowers on strong stems. Native Echinacea has been bred extensively into many colors and habits, some of which are so different from the parent plant they become unusable to insects. Research continues as to whether changing the color of the flower so drastically is detrimental to pollinators. Photo courtesy of Walter’s Gardens.

Other important terms you may want to be aware of for future posts:

Diploid and Tetraploid – the number of chromosomes in the plants cells. Diploid plants have two sets of chromosomes, tetraploid have four sets. Both occur in the natural world, and one is not necessarily better than the other, though tetraploid plants do show some benefit in yield, palatability, and vigor.

F1 hybrid plant or seed – product of the pollination of two different parent plants, short hand for Filial 1, or “first children”. This can happen naturally, as in the case of peppermint. But it is often it is performed by humans to create disease resistant and more desirable plants. It is responsible for huge advances in the food stability and supply of important crops. This kind of plant breeding was studied and recorded carefully by monk Gregor Mendel over 150 years ago!

Controlled Pollination – purposefully transferring pollen from one plant to the receptive female stigma of another plant, while removing the possibility for other pollen to fertilize that plant. At its simplest, controlled pollination is doable by the home gardener with the desired pollen dusted on a paintbrush, tweezers to remove the male anthers on the flower (if the flower is bisexual), a plastic bag to keep out any other wind-born pollen.

Subspecies – a taxonomic distinction just below species, meant to indicate a group within a species that is distinctly different but still close enough to be interbred with the species. Usually a subspecies is somewhat geographically isolated. Often confused with a variety, and sometimes a plant initially identified as a variety eventually becomes designated as subspecies.

Know Better, Do Better

A paraphrase from Maya Angelou, this saying is applicable in all parts of life, including gardening! Knowing the terminlogy of the trade ultimately helps us make better decisions in our gardens. Scientific lingo is cold and uninviting, but we shouldn’t just dismiss certain plants as “unnatural” just because the terms are poorly understood. In trying to do our best for pollinators and the prairie ecosystem, information is power. Stay tuned for future posts that about how we decide which cultivars are useful on our grounds and which to avoid, how to spot a patented plant, when is the best time to use straight natives only, and how to make some native clones of your own!