Species, varieties and cultivars

[Bonsai Nut]

On this site we have some confusion about the difference between species, variety and cultivar, so I thought I would post a quick reference on taxonomic rank.

Taxonomy is the science of classifying organisms. Taxonomic rank (or hierarchy) is simply the most efficient way that has been developed to date to classify / name all living creatures. Most people are familiar with the taxonomic ranking scale: Kingdom / Phylum / Class / Order / Family / Genus / Species. This article deals with the lowest level of this scale - species - and additional classification below the species level that applies specifically to plants (organisms in the "Plantae" Kingdom).

SPECIES
The lowest level of classification, species is defined as the largest group of organisms that are so genetically similar that they can reproduce and produce fertile offspring. There are exceptions to this rule, but for the purposes of this article we will skip over them. It is really important to understand that when talking about plants, species BREED TRUE (or in the case of plants, the term "seed true" is also used). What that means is that if you have two parent plants that produce seeds, the seedlings will belong to the same species. When discussing plants, we may refer to them by their common name "Chinese elm" or their binomial (or Latin) name Ulmus parvifolia. Latin names are made up of two words - the GENUS name and the SPECIES name of the organism. In the example of Ulmus parvifolia, Ulmus identifies the elm genus, and parvifolia identifies it as a Chinese elm.

When trying to be specific, it is best to use Latin names, because they are unique to the species. Common names are vague, inexact, and can sometimes refer to more than one species, and sometimes one species can have more than one common name. Additionally, all languages / countries use the same Latin names. Common names often differ by language or location.

When writing a Latin name, the genus name is capitalized, and the species name is not. The name is italicized. It can be abbreviated with one letter of the genus (U. parvifolia). When referring to all members of a genus, it is common to see the term "species" abbreviated and used with the genus name: Ulmus sp. (meaning one type of elm) or Ulmus spp. (meaning several types of elms). Enough about typing...

SUBSPECIES and VARIETY
Subspecies and variety are one level lower on the taxonomic scale. All members of a subspecies or variety belong to the same SPECIES, and they can breed with other members of the species whether those individuals belong to the subspecies or not. The traits that make subspecies and variety members unique are genetically inheritable - ie they SEED TRUE when two individuals of the same subspecies or variety produce offspring.

SUBSPECIES are a specific group of individuals that all share a common trait (or traits) different from the species members at large, and are usually limited to a specific geographic area.

VARIETY are a specific group of individuals that all share a common trait (or traits) different from the species members at large, and are NOT limited to a specific geographic area.

Subspecies and variety are indicated by the abbreviations "subsp." or "var." in their Latin names. For example: Acer buergerianum var. formosanum, or Acer pictum subsp. mono.

A practical example of variety might be if one type of flower found in the wild usually has white flowers, but occasionally is found with blue flowers, and if you breed two blue flowers together all of the seeds produce plants with blue flowers. A practical example of subspecies might be if one type of flower in the wild has white flowers, but on one island in the Pacific it only has blue flowers. All of these flowers only produce blue flower offspring.

Varieties can sometimes be man-made via selective breeding. These varieties differ from cultivars because they seed true and their offspring maintain the desirable characteristics of the parent plants.

CULTIVAR
The easiest way to think about cultivars is (1) they are man-made and do not occur in nature and (2) they do not seed true - and must be cultivated via cutting, graft or other clonal method. Cultivars are plants that have been selectively propagated for desirable characteristics, like prettier flowers, larger fruit, disease resistance, etc. In some cases the plants may not even be fertile, though in other cases they may be fertile and produce offspring more or less similar to the cultivar holotype (but not the same). In current times, cultivars can represent valuable intellectual property for the individual or organization that created them - think of Monsanto, Round-Up herbicide, and their line of Round-Up resistant food crop cultivars.

Cultivars are indicated by single quotes in the Latin name, and the cultivar name is not italicized. For example: Ulmus americana 'New Harmony' or Ulmus americana 'Jefferson' - two American elm cultivars that are resistant to Dutch elm disease.

Because cultivars are maintained via clonal reproduction, all offspring are genetically identical to the original holotype. All Valencia orange trees, for example, are genetically identical to the first original Valencia orange. If you took a seed from a Valencia orange tree, planted it, and got a tree to grow, that tree would not be considered a Valencia orange, though it might have many/most of the characteristics of one. This is particularly the case when you consider cultivars of genetically variable genera like Ulmus or Acer, or situations where it might be difficult to identify both parent trees.

Discuss

 

[Adair M]

On this site we have some confusion about the difference between species, variety and cultivar, so I thought I would post a quick reference on taxonomic rank.

Taxonomy is the science of classifying organisms. Taxonomic rank (or hierarchy) is simply the most efficient way that has been developed to date to classify / name all living creatures. Most people are familiar with the taxonomic ranking scale: Kingdom / Phylum / Class / Order / Family / Genus / Species. This article deals with the lowest level of this scale - species - and additional classification below the species level that applies specifically to plants (organisms in the "Plantae" Kingdom).

SPECIES
The lowest level of classification, species is defined as the largest group of organisms that are so genetically similar that they can reproduce and produce fertile offspring. There are exceptions to this rule, but for the purposes of this article we will skip over them. It is really important to understand that when talking about plants, species BREED TRUE (or in the case of plants, the term "seed true" is also used). What that means is that if you have two parent plants that produce seeds, the seedlings will belong to the same species. When discussing plants, we may refer to them by their common name "Chinese elm" or their binomial (or Latin) name Ulmus parvifolia. Latin names are made up of two words - the GENUS name and the SPECIES name of the organism. In the example of Ulmus parvifolia, Ulmus identifies the elm genus, and parvifolia identifies it as a Chinese elm.

When trying to be specific, it is best to use Latin names, because they are unique to the species. Common names are vague, inexact, and can sometimes refer to more than one species, and sometimes one species can have more than one common name.

When writing a Latin name, the genus name is capitalized, and the species name is not. The name is italicized. It can be abbreviated with one letter of the genus (U. parvifolia). When referring to all members of a genus, it is common to see the term "species" abbreviated and used with the genus name: Ulmus sp. (meaning one type of elm) or Ulmus spp. (meaning several types of elms). Enough about typing...

SUBSPECIES and VARIETY
Subspecies and variety are one level lower on the taxonomic scale. All members of a subspecies or variety belong to the same SPECIES, and they can breed with other members of the species whether those individuals belong to the subspecies or not. The traits that make subspecies and variety members unique are genetically inheritable - ie they SEED TRUE when two individuals of the same subspecies or variety produce offspring.

SUBSPECIES are a specific group of individuals that all share a common trait (or traits) different from the species members at large, and are usually limited to a specific geographic area.

VARIETY are a specific group of individuals that all share a common trait (or traits) different from the species members at large, and are NOT limited to a specific geographic area.

Subspecies and variety are indicated by the abbreviations "subsp." or "var." in their Latin names. For example: Acer buergerianum var. formosanum, or Acer pictum subsp. mono.

A practical example of variety might be if one type of flower found in the wild usually has white flowers, but occasionally is found with blue flowers, and if you breed two blue flowers together all of the seeds produce plants with blue flowers. A practical example of subspecies might be if one type of flower in the wild has white flowers, but on one specific island in the Pacific it only has blue flowers. All of these flowers only produce blue flower offspring.

Varieties can sometimes be man-made via selective breeding. These varieties differ from cultivars because they seed true and their offspring maintain the desirable characteristics of the parent plants.

CULTIVAR
The easiest way to think about cultivars is (1) they are man-made and do not generally occur in nature and (2) they do not seed true - and must be cultivated via cutting, graft or other clonal method. Cultivars are plants that have been selectively propagated for desirable characteristics, like prettier flowers, larger fruit, disease resistance, etc. In some cases the plants may not even be fertile, though in other cases they may be fertile and produce offspring more or less similar to the cultivar holotype (but not the same). In current times, cultivars can represent valuable intellectual property for the individual or organization that created them - think of Monsanto, Round-Up herbicide, and their line of Round-Up resistant food crop cultivars.

Cultivars are indicated by single quotes in the Latin name, and the cultivar name is not italicized. For example: Ulmus americana 'New Harmony' or Ulmus americana 'Jefferson' - two American elm cultivars that are resistant to Dutch elm disease.

Because cultivars are maintained via clonal reproduction, all offspring are genetically identical to the original holotype. All Valencia orange trees, for example, are genetically identical to the first original Valencia orange. If you took a seed from a Valencia orange tree, planted it, and got a tree to grow, that tree would not be considered a Valencia orange, though it might have many/most of the characteristics of one. This is particularly the case when you consider cultivars of genetically variable genera like Ulmus or Acer, or situations where it might be difficult to identify both parent trees.

Discuss

Everything you just posted is true.

In the bonsai world, we scramble things up a bit. Many trees get “foliage changed”. For instance I have a Western juniper that I grafted “kishu” shinpaku juniper onto. When the grafts took, I jinned the remaining Western foliage. The trunk and roots are Western, the foliage is Kishu. When I take this to a bonsai show, it will listed as a “juniperus chinesis ‘shinpaku kishu’”. That’s the Latin name for the foliage. The trunk doesn’t get a mention.

Likewise, I have a Japanese White Pine that was originally a lodgepole. The JWP was grafted on 25 years ago. It is shown as being a JWP.

 

[cheap_walmart_art]

Very succinct. Thanks for laying out that information!

 

[Gustavo Martins]

Some add-ons

When writing a Latin name, the genus name is capitalized, and the species name is not. The name is italicized.

It is not mandatory that it is italicized. What it is mandatory is that it is written in a different way (italics, underlined, whatever) to be easily differentiated from the remaining text. Same would happen if you write a French word in the middle of a English text.

Subspecies and variety are indicated by the abbreviations "subsp." or "var." in their Latin names. For example: Acer buergerianum var. formosanum, or Acer pictum subsp. mono.

Not necessary to have "subsp." or "var" written down. It could be simply written as Homo sapiens sapiens.

More:
There are many abbreviations that can be used mixed in the Latin name:
Acer cf. buergerianum - means that it needs confirmation of the ID
Acer aff. burgerianum - Means that is similar to...

 

[Bonsai Nut]

In the bonsai world, we scramble things up a bit. Many trees get “foliage changed”. For instance I have a Western juniper that I grafted “kishu” shinpaku juniper onto. When the grafts took, I jinned the remaining Western foliage. The trunk and roots are Western, the foliage is Kishu. When I take this to a bonsai show, it will listed as a “juniperus chinesis ‘shinpaku kishu’”. That’s the Latin name for the foliage. The trunk doesn’t get a mention.

In California, most grafted plants (particularly fruit trees and grapes) come with two tags - one for the graft scion and one for the root stock. You can grow Valencia oranges, for example, on many different root stocks, depending on location and the attributes you are seeking. In some cases, the best root stock might even be a lemon or tangelo

There are an almost uncountable number of wine grape cultivars in America and Europe, but they are almost all grown on American vine root stock, which has natural resistant to phylloxera, a grape pest that almost wiped out European grape stock.

There are many abbreviations that can be used mixed in the Latin name:
Acer cf. buergerianum - means that it needs confirmation of the ID
Acer aff. burgerianum - Means that is similar to...

There are even some cases, in the case of a hybrid or cultivar, where there is no species name.

 

[Wires_Guy_wires]

Inbred cultivars can breed true. Some cultivars come from a long line of inbreeding to get all of the characteristics lined up and in check. Crossing those cultivars, would be similar to 'selfing' or autofertilisation.
If they're inbred enough, nothing will change apart from eugenetic factors, which also influence cutting behavior.

Not all cultivars stay true, some have dominant genes at one age, and other dominant genes at another age. This is especially the case when a cultivar gets it's preferred traits from two dominant and thus competing genes.


Now, it's not a real genetic trait, but still a good example: violets. When you get them from the store, they are pretty big. If you make a clone every year, after 3 or 4 years they'll stay penny sized. This is due to the loss of nuclei; violets are treated with colchicine to become polyploid, but that polyploidity is lost after cloning a few times.

 

[Vin]

Great content! I may add that when dealing with cultivars, many are patented as in my Ulmus parvifolia 'Drake'. It seeds profusely most years and I'm left with thousands of seedlings. By way of example, I was told legally I cannot identify them as 'Drake Elm" but instead should/can call them "seedlings from a Drake Elm". Please correct me if I am wrong.

 

[Bonsai Nut]

Likewise, I have a Japanese White Pine that was originally a lodgepole. The JWP was grafted on 25 years ago. It is shown as being a JWP.

The only way to grow Japanese white pine in Southern California is to graft it on Japanese black pine root stock. In fact, many ornamental growers of Japanese white pine cultivars use Japanese black pine regardless, because the root stock is much more vigorous than Japanese white pine's own roots.

 

[Smoke]

Everything you just posted is true.

In the bonsai world, we scramble things up a bit. Many trees get “foliage changed”. For instance I have a Western juniper that I grafted “kishu” shinpaku juniper onto. When the grafts took, I jinned the remaining Western foliage. The trunk and roots are Western, the foliage is Kishu. When I take this to a bonsai show, it will listed as a “juniperus chinesis ‘shinpaku kishu’”. That’s the Latin name for the foliage. The trunk doesn’t get a mention.

Likewise, I have a Japanese White Pine that was originally a lodgepole. The JWP was grafted on 25 years ago. It is shown as being a JWP.

You didn't even graft on a species. You grafted on a cultivar which makes it really a hillbilly. The juniper that is......

 

[BrianBay9]

I've always dealt with animal taxonomy professionally. The other confusing thing about plants is that clearly identified species can still hybridize between other species in the genus, and result in offspring that produce viable seeds. Examples are many California oaks or species of elm. It's possible that identification of species has been more difficult in plants. In other words the concept of species seems a bit looser in plants than in most animals. Of course it can happen in animals, mostly with human help (mules, ligers) but generally they are not fertile. Maybe species seem more 'secure' because animals exhibit behavior segregation that also keeps species from hybridizing.

 

[Adair M]

You didn't even graft on a species. You grafted on a cultivar which makes it really a hillbilly. The juniper that is......

And your point is?

 

[Bonsai Nut]

I've always dealt with animal taxonomy professionally. The other confusing thing about plants is that clearly identified species can still hybridize between other species in the genus, and result in offspring that produce viable seeds. Examples are many California oaks or species of elm. It's possible that identification of species has been more difficult in plants. In other words the concept of species seems a bit looser in plants than in most animals. Of course it can happen in animals, mostly with human help (mules, ligers) but generally they are not fertile. Maybe species seem more 'secure' because animals exhibit behavior segregation that also keeps species from hybridizing.

Probably the best current example of this right now is the coywolf (coyote / wolf hybrid).



Coywolves are taking over Eastern North America

 

[Smoke]

The point is this whole thread. All tridents are Acer buergerianum whether they come from China, Formosa, USA or Europe. Untill you change the second name it is still the same species. The third names are just nursery industry names for differences in the trees. They can be natural mutations or nursery induced mutations, but mutations just the same.

We are all humans, Home sapiens. We have a lot of mutations. But when you cut us, we all have the same sap.

 

[Smoke]

I think the wolf coyote hybrid has nothing to do with plant taxonomy.

We have almost 98 percent DNA capability with Chimpanzees and we can't mate with them. I was in Tijuana one time and did see a guy try though???

Wolfs and coyotes just happen to carry the same of everything to make a hybrid possible.

As far as I know, I have seen hybrid citrus and stone fruit. But I have never seen anyone change the classification of acer palmatum and acer buergerianum to make a acer palmatum x acer buergerianum or Acer palgerianum. Now that would be something.

 

[Ohmy222]

Crabapples don’t care about the rules

 

[Adair M]

I think the wolf coyote hybrid has nothing to do with plant taxonomy.

We have almost 98 percent DNA capability with Chimpanzees and we can't mate with them. I was in Tijuana one time and did see a guy try though???

Wolfs and coyotes just happen to carry the same of everything to make a hybrid possible.

As far as I know, I have seen hybrid citrus and stone fruit. But I have never seen anyone change the classification of acer palmatum and acer buergerianum to make a acer palmatum x acer buergerianum or Acer palgerianum. Now that would be something.

Again, what point are you trying to make?

I have a trident maple, a pretty rare cultivar: a Miso Yatsabusa. The leaves have very long central lobes, that droop. Makes the tree have a “weeping willow” look. I suspect it was propagated via cutting. I’ve seen a couple others at Johnny Uchita’s Grove Way nursery. Never seen anything like it here at home.

JRP and JBP are closely related. They can hybridize. They tend to resemble JBP more, but have red buds. Stuff happens.

 

[Gustavo Martins]

Ability to mate and produce fertile offspring is just one definition of species. It clearly works with some ‘kinds’ of species but it is not so appropriate with other (e.g. bacteria, virus, prions, etc) There are others definitions of species.

At the end of the day, this is an artificial classification made by humans.

 

[Michael P]

Thank you for a much needed clarification. Those of us who deal with plant taxonomy professionally know that there are many complexities and it is impossible to cover them all in a brief explanation. But in the vast majority of cases, the key principles of genus, species, and subspecies/variety/cultivar will suffice.