Starting the journey of learning plant scientific names can be scary!
Words in alien languages such as ancient Latin and Greek hardly come naturally to any of us, so it’s no wonder that we gardeners rarely ever get into learning the “true” names for the plants we see and work with every day.
This article isn’t intended to preach to you and tell you that you should learn the scientific names for every single plant. Instead, this article serves as a guide to help you navigate the territory.
By the end of the post, you should know why scientific names are useful, what the heirachy of the names and classifications are, and why some names are italicised while others aren’t.
With this info you’ll be able to better understand the levels of plant relatives and recognise multiple species within the same genus by looking at their names.
The Natural Classification System
The natural classification system is the scientific way of classifying plants, where we group plants together which we believe are more closely related through evolution. I say “believe” because these classifications shift and change as we learn more.
Scientists used to classify all organisms as either plants or animals. This way of classifying organisms proved to be fraught with problems because there were many, many organisms that just didn’t quite fit.
For example, questions like “if fungi are plants, why do they breathe in oxygen and exhale carbon dioxide like an animal?” arose.
As a result, we had to add more classifications to fit what we actually see in biological organisms.
Today, we usually talk about 6 main kingdoms that almost all organisms fit within. Those kingdoms are Animalia, Plantae, Fungi, Protista (algae), Bacteria and Archae (bacteria-like organisms that live without oxygen).
There are some weird organisms out there that still elude classification or are haphazardly bundled in, especially among simpler forms, and there is still much debate about where certain types fit.
This blog, Plants Grow Here, likes to focus on (you guessed it!) the plant kingdom, although it’s impossible to talk about plants for very long without speaking about the other kingdoms seeing as how all life is connected.
We can break the plant kingdom down further into four groups: bryophytes (mosses and liverworts), pteridophytes (ferns), gymnosperms (cone-bearers), and angiosperms (flowering plants).
You can read my article about the four plant groups here.
These four groups of plants represent the four major evolutionary developments in plants, and they can all be broken down further into a further series of groups that become more specific until you reach the species level.
For example, angiosperms can be broken down into two groups: monocots and dicots, and you can read more about the difference between these two groups in the article I wrote here.
The Layers Of The Scientific Names Of Plants
All plants have a common group of ancestors and have branched out from the original plants that crawled out of the ocean. Each lineage has been through a lot of changes since then and we can scientifically classify plants by tracing their ancestral lines.
Of course, as mentioned above, the scientific understanding and consensus changes over time.
We use the following heirachy of scientific classifications: kingdom, division, class, order, family, genus, species.
Kingdom is the least specific classification which holds all plants within it, and species is the most specific classification that points only to one individual type of plant.
Let us classify Australia’s floral emblem, the golden wattle (Acacia pycnantha) as an exercise.
The first and easiest classification to group them into is their kingdom, which for all plants will always be the Plantae kingdom, including our wattle.
Immediately below the plant kingdom we can recognise that this plant has flowers, making it of the Angiosperm division.
Angiosperms are broken down into two classes: Monocots and Dicots. Wattles are of the Dicot class.
Below the class we have the order, and wattles belong to the Fabales order which hosts a massive number of plant species, including the famous “sensitive plant” that provided my brothers and I endless fun as children when we’d touch the leaves to make them fold.
Another step down and we have Fabaceae, or the legume family. This means that wattles are surprisingly quite closely to other legumes such as peas and beans. Like other members of the legume family, wattles have bean pods and the ability to fix nitrogen but the wattle flower is very different to other family members.
The subfamily that wattles belong to is Mimosaceae. Sensitive plants are part of this family, but plants that we normally think of as legumes (such as beans, peas and clovers) have now split off. Plants within this subfamily generally have fluffy pom-pom-like inflorescences.
Once we get to the genus level, we are getting very specific. All wattles belong to a single genus, Acacia, which doubles as a colloquial name that’s interchangeable with “wattle”. The plural of genus is genera.
And the final classification we listed above would be the species, pycnantha, which we would colloquially call the “golden wattle”, or simply an “acacia”.
The scientific method is to use the genus and species scientific names together. In this case, we get the scientific name Acacia pycnantha.
If the species cannot or need not be identified, you can abbreviate the second word to sp., for example “one Acacia sp“.
If there are multiple species within a genus being referred to, you can use spp., for example “many Acacia spp“.
As you can see, this name gives us access to an absolute abundance of information. If we know the genus, we can work our way right back up the chain and can have a good idea of where the organism fits in regards to its plant relatives.
Any plant that has the same genus name will be closely related. However, be careful because some plants have the same species name even though they are in a different genus, or even family.
Subspecies, Variety & Form
In nature there are often very slight differences between plants, for example one species may exist in two separate environments and could have very tiny variations.
For example, Acacia dealbata is a variation of wattle that has a couple of forms: Acacia dealbata ssp dealbata and Acacia dealbata ssp subalpina.
The first subspecies (ssp dealbata) occurs naturally at altitudes of around 350-1000m above sea level and grows as a large shrub (or small tree) of around 6m tall. The second subspecies (ssp subalpina) grows in higher country in the ACT and and Victoria and usually only gets up to about 3m tall.
Even though though they’re the same species, there is a bit of genetic variation due to the differences in their ancestral environment.
As you can see, with subspecies we use “ssp” (not “spp” like you use when you are referring to multiple species within a single genus). The ssp is not italicised, hence why we write Acacia dealbata ssp subalpina.
A variety is a classification below subspecies, and form is a classification below variety. These terms are used when we’re being very specific about the tiny differences between plants.
The word cultivar is a combination of the words “cultivated” with “variation”, and means plants that humans have bred with specific traits in mind, for example juicier fruit or brighter flowers.
Cultivar names can be a bit different in that they might not have a valid scientific name for the genus or species and so may or may not have one or two words italicised. Pay attention when cultivar names are not italicised, because this may be the correct way to write the scientific name of that variety.
Australia’s Virtual Herbarium gives three examples of cultivar names for two plants:
Grevillea ‘Robyn Gordon’ is a grevillea cultivar that’s a hybrid between two different species.
Grevillea rosmarinifolia ‘Rosy Posy’ is a cultivar that was bred from a naturally occurring species, Grevillea rosmarinifolia.
Grevillea ‘Rosy Posy’ is an acceptable name for the same plant as Grevillea rosmarinifolia ‘Rosy Posy’, but this naming method lacks the species name rosmarinifolia and so is less informative.
Hybrid plants may have an “x”, such as Fragaria × ananassa which is a hybrid commonly called the garden strawberry. Yep, that garden strawberry.
Why Should We Use Scientific Names?
We all use colloquial terms when we talk about plants. If I were talking about Acacia pycnantha, I’d probably just call it a “wattle” or “acacia”.
While this is totally fine if I’m pointing to the plant as I’m talking about it, were I looking to study any possible medicinal effects of the plant, “wattle” just isn’t going to be specific enough because each species will have their own properties.
Another problem can be that sometimes, multiple plants share a colloquial name, for example if I were to say “grab me a mock orange from the nursery”, depending on where you are in the world you could come back with a plant from at least three totally separate genera: Choisya, Murraya or Philadelphus.
A third problem is that many plants have multiple names for the single plant. I might be standing here saying “this is a seaside daisy”, you’re there saying “no it’s an erigeron”, someone else is saying “no, it’s seaside fleabane” while a fourth person is shaking their head saying “actually this is sea aster”. We’d all be right, because these are all equally valid colloquial names referring to the plant that is scientifically called Erigeron glaucus.
What Do Scientific Names Mean?
Most scientific names are in Latin with some in Greek, as well as other languages including a few aboriginal Australian words thrown in there too.
They tend to point towards characteristics of the plant group. For example, eucalypts are named after the Greek words “eu” meaning good or beautiful, and “kalypto” meaning concealed or hidden, which refer to the characteristic cap that covers eucalyptus flower buds.
Recognising vs. Identifying Plants
There are already a wide variety of plants that you recognise. You know a rose bush when you see one, even if you can’t identify the particular cultivar, such as Rosa ‘KORbin’.
The process of identifying plants includes research as you stare at your plant compared to taxonomical descriptions and photos. Once you’ve identified it, you can then recognise the same species elsewhere.
If Sally and Tim walked past a rose bush and Tim said “that’s a Rosa ‘KORbin’, the iceberg rose” and then Sally took some photos, went home and decided that yes this plant was an iceberg rose, Tim would have recognised the plant and Sally would have identified it.
You can recognise or identify a plant at any level, whether class, family, genus or species. I might be able to positively identify a member of the pea family without having yet identified which species it is.
Of course, it’s human beings who like to classify things. The actual organisms don’t need to name the group they belong to, they just do their own thing and major changes to their DNA are done over vast spaces of time as groups become more and more refined, and more and more differentiated from common ancestors.
Botanists are still discovering new species and naming them, and they’re also changing existing classifications as scientific understanding becomes higher in resolution through the relentless plants. Names are constantly changing as plants are re-categorised into new genera.
Even if you don’t use scientific names, it’s just good to know that they exist and that you can look them up at any time with a quick Google search of the common name. Just make sure to check photos so you know Google knows the actual plant you’re talking about!
Where To From Here?
Continue your plant classification journey by reading my article on identification using flowers and leaves or browse some commonly planted families, subfamilies and genera.