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What's in a Name? Native Plant Terminology

Updated: Jan 8


Asclepias tuberosa, Butterfly Weed, flowers and plant label
An example of a straight species: Asclepias tuberosa, commonly called Butterfly Weed.

Know your plant terminology: Species, Selections, Varieties, Cultivars, and Hybrids


When you begin to be interested in native plants, soon you may start hunting for plant labels to find out the names of new and interesting plants you come across. You begin to notice and hear people using different terminology: "This is a compact cultivar," or "We sell only local ecotype natives," or "That's not native; it's a hybrid."


What do these terms all mean, and how can you keep them straight?


Get ready. We are about to dive in. And don't worry, because I have made a handy, downloadable chart for your reference! Scroll down if you want to grab it.


What is a native plant?


First, let's talk about native vs. non-native plants. In short, a native plant is a species that co-evolved with the other plants and and animals in a particular place, without human intervention. How you define "place" is where all of the discussion about native vs. non-native gets tricky. I plan to write more about this subject in the future, but for now, let's consider the "place" to be your ecoregion - an area where ecosystems are generally similar. You can find out what your ecoregion is on the EPA website. In practice, you might want to make it easier on yourself and look into what plants are native to your county, and/or neighboring counties. In Northern Virginia, we have some excellent online resources on native plants. To get a comprehensive list of native species by county, visit the Digital Atlas of the Virginia Flora and click on your county. Plant Nova Natives also has a very helpful, searchable database with images and attributes listed for each plant, although it is not as comprehensive as the Digital Atlas. Finally, Earth Sangha, a native plant nursery in Alexandria, VA, has a very interesting plant list and information on plants that belong to selected plant communities on their website.


Map of Level III and IV Ecoregions of EPA Region 3: PA, WV, MD, DE, VA, DC
Ecoregions of the Mid-Atlantic.

A non-native plant is a plant that evolved in a different environment, and usually does not have the same associations with insects and other animals as a native plant. This is why so many of our common ornamental and invasive plants (which originated in Europe, Asia, or elsewhere) don't get holes in their leaves: the insects that eat them don't occur here!


The reason that the native vs. non-native debate is so important is that our landscape is under such enormous human pressure. Development and disturbance have widely impacted our native ecological communities. Non-native, invasive plants have moved into many undeveloped areas too, displacing native plant communities. As a result, our insects - which form a foundational tier of our natural food web - have less to eat. The animals that eat the insects therefore also have less to eat. By adding native plants to your landscape, you are supporting wildlife and biodiversity. This biodiversity is a key factor in sustaining human existence.


Species, Straight Species, and Local Ecotype Natives


OK, back to the terminology discussion. Straight species, or species, refers to the naturally occurring form of any plant. Every species has a botanical name made up of two parts: the genus and the specific epithet. Botanical names are always rendered in italics, with the genus capitalized and the specific epithet written in lower case. For example:


Black-eyed Susan plant and label: Rudbeckia fulgida

Rudbeckia fulgida

[Genus + specific epithet]

(commonly called Black-eyed Susan), belongs to the genus Rudbeckia - of which there are numerous species. This species is denoted as fulgida. If you grow out the seeds of a straight species, the progeny will grow up true to form, meaning that they will have the same characteristics as the parent plants. Natural genetic diversity is preserved in seed propagation: the gene pool of the population naturally mixes through pollination and fertilization, and random genetic combinations occur. This is healthy and necessary for the continued adaptation and evolution of the plant's population.


To get even more specific (was the pun intended? it just came out), populations of species can vary regionally. Acer rubrum, red maple, has an enormous natural range that extends from Newfoundland down to southern Florida, and west to Minnesota and Texas:


Range map of Acer rubrum, Red maple.
Range of Acer rubrum, Red maple. Source: Wikimedia Commons

Although trees found at each extreme belong to the same species, individuals transplanted from one end of that range to the other would not be well-adapted to their surroundings. Local ecotype natives refers to plants that originated nearby, in a similar region, ecosystem, or habitat. These are the gold standard when choosing native plants to add to your landscape, because by planting and propagating them, you are supporting the naturally occurring local population of that species. When you plant native species that originated several states away, their genes could mix with the local population and introduce traits that are less specifically suited to local conditions. It can be more difficult to source local ecotype natives, but certainly is worth the effort.


Subspecies


A Subspecies is a naturally occurring, distinctive population of a species, usually found in a particular geographic region. Plants of a subspecies differ from the general species in their shape, size, or other physical traits.


small round cactus in a terra cotta pot, Mammillaria albilanata subsp. oaxacana

Mammillaria albilanata subsp. oaxacana

[Genus + specific epithet + subspecies]


Subspecies are identified with a three-part botanical name, or trinomen: First the genus, then the specific epithet, then the subspecies name. Each part of the name is italicized, and only the genus is capitalized. It's easily recognized by the "subsp." abbreviation, also sometimes written as "ssp." The abbreviation is never italicized or capitalized. Seedling offspring of a subspecies generally grow true to type, and natural genetic diversity is preserved through sexual (seed) reproduction.


Variety


A Variety is a naturally occurring subset of a species with one or more distinct characteristics from the general species. It can interbreed with any other member of the species. Seedling offspring will generally exhibit the same traits as their parents. Natural genetic diversity is passed on between generations with seed reproduction. Taxonomically, variety is a category just below subspecies. Varieties are not genetically isolated from the rest of the species like most subspecies are due to geography.


Plant label on tree trunk: Davidia involucrata var. vilmoriana, Dove tree

Davidia involucrata var. vilmoriana

[Genus + specific epithet + variety]


Just like subspecies, a variety gets a trinomen: Genus, specific epithet, and variety name. The variety is denoted by the unitalicized abbreviation "var."


Cultivars: Selections, Nativars, Hybrids, and Patented Plants


A Cultivar is a cultivated variety: a selection within a species, where the distinctive characteristics have been intentionally cultivated. Cultivars can result from several human actions: deliberate cultivation of a naturally occurring variant; breeding a cross between two species or genera; or deliberate genetic manipulation to create a distinctive variety.


Selection or Nativar


A Selection is a cultivated variety whose origin or selection is primarily due to human action. Plant breeders grow out distinctive examples until their desired traits are reliably reproduced, or simply begin vegetatively propagating (cloning) the original example plant to create clones. Selections are given names to identify the particular variety. A Nativar is not a technical term, but rather a shorthand for native cultivar. Of course, the term "nativar" is relative to where it is used.


Iris versicolor 'Purple Flame'

Iris versicolor 'Purple Flame'

[Genus + specific epithet + cultivar epithet]

A selection is denoted by its species name followed by its cultivar epithet, unitalicized, capitalized, and contained within single quotes. The cultivar epithet can be a common word, term, or a proper name, but it cannot be a Latin word. Depending on the origin of the selection, seedling offspring may not grow out true to type. With vegetative reproduction (by division, stem, root, or leaf cuttings, or through tissue culture), genetic diversity is not preserved: every plant is a clone of the original, with exactly the same set of genes. This is the case with most cultivars sold in nurseries and plant catalogs.


Hybrids

A Hybrid is a cross between two species, or occasionally between two genera. In the context of gardening and landscaping, it is usually a cultivar, although there are naturally occurring hybrids (oaks and penstemon are two kinds of plants that can readily hybridize among species). Food plants are very commonly hybridized, because the first generation of a cross, known as an F1 hybrid, often shows greater health and vigor than its parents. You've probably seen vegetable seed catalogs with tomatoes and sweet corn touted as being "high yield" F1 hybrids.


Two cats in front of a catmint plant, Nepeta x faassenii 'Walker's Low'

Nepeta x faassenii 'Walker's Low'

[Genus + x + hybrid specific epithet + cultivar epithet]

Hybrid nomenclature varies depending on the hybridization technique. Above, 'Walker's Low' catmint is shown. It is an interspecific hybrid, meaning that two species were crossed to create the cultivar. In this case, the nomenclature is written as the genus followed by an unitalicized x, followed by the hybrid specific epithet, followed by the cultivar name. Nepeta x faassenii 'Walker's Low' is a cross between N. racemosa and N. nepetella. It is named for J. H. Faassen, the breeder who developed the first hybrid. The particular cultivar, 'Walker's Low', was then selected from the hybrid species.


To make things even more confusing, if a hybrid results from crossing two genera, it is sometimes written with the x in front of the genus name, as in x Agropogon littoralis. Not all hybrids have cultivar epithets. And sometimes a hybrid is simply written with the genus followed by an x. The basic theme here is, if you see an "x" in the name, you know that it is a hybrid! Also, when pronouncing these names out loud, you say the "x". To go back to the catmint example in the image above, it would be pronounced "Nuh-PET-uh EX Fass-EEN-ee-eye Walker's Low".


As you might expect, the seedling offspring of hybrids often do not come true to form. Hybrid cultivars are propagated vegetatively, so every 'Walker's Low' catmint plant is a genetic duplicate. Natural genetic diversity obviously is not preserved in hybridization and propagation.


Patented Plants


Patented plants are cultivars whose owners have legally protected the selection. They may not be propagated, bred, or sold except by the patent holder or their licensee. Licensees pay royalties to the patent holder. You can spot these immediately by the patent number or the all-caps term on the label.


Daphne x transatlantica 'BLAFRA'

[Genus + x + hybrid specific epithet + cultivar epithet]

'Eternal Fragrance' Daphne, pictured above, is a patented hybrid cultivar. 'Eternal Fragrance' is the trademarked name. Patents last for 20 years. Anyone caught propagating or selling them without a license can face hefty fines. This system is intended to protect the breeders and developers and to insure that their work is compensated.


TL;DR (Too Long; Didn't Read)


Phew! That is a lot of terminology. If you did not have the desire or patience to read this entire post, not to worry. Here is a handy chart that sums everything up, from species to cultivar:


Plant terminology quick reference guide

Download the .pdf by clicking the image above.




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