Why has the name of your plant changed?

Have you ever been confused when a plant’s scientific name suddenly changes? It can feel like your favorite plant is having a mid-life identity crisis.
The Mother-in-law's Tongue, for instance, has been known as Sansevieria for as long as most of us can remember, but now it’s suddenly grouped with Dracaena.

Why does this happen? Is it just scientists trying to keep us on our toes? Let’s dig into the history of how we scientifically name plants.

A brief history lesson on botanical names

Polynomials

In the early days of Western botany, plants were known to the public by local common names, while scientists identified them using long, descriptive Latin phrases known as polynomials. Imagine trying to talk about a plant called Albus erubesco major comosus esculentus. While that's a made-up example, it translates to "large, white, slightly blushing, hairy, and edible." Helpful for identification? Maybe. Easy to use in a conversation? Definitely not.

Another problem was that these polynomials weren't standardized. Different botanists could use different descriptive combinations for the exact same plant. A real-world example of this linguistic mouthful is the original name for the tomato: Solanum caule inermi herbaceo, foliis pinnatis incisis. This literally means "Solanum with the smooth herbaceous stem and incised pinnate leaves."

Binomial system

In the 18th century, Carl Linnaeus simplified this chaos by popularizing the binomial system. Instead of a long paragraph, every plant was given just two names: a Genus and a species epithet.

Today, that complicated tomato is simply Solanum lycopersicum. Together, the two parts of the name refer to the tomato species.

However, the genus Solanum , is a group that also contains many other species. Think of the genus like a last name that comes first. It tells you these plants are all closely related cousins. For example Solanum tuberosum, Potato and Solanum melongena, Eggplant.

The binomial system uses two names, but it is actually part of a much larger system that categorizes plants into a massive family tree. While we only use the genus and species for the official name when we write them, they belong to even larger groups that show deeper ancestral connections.

Thanks to Linnaeus, we use a standardized, two-part scientific name that is recognized by gardeners and scientists worldwide.

Morphology and the Human Factor

For centuries, plant classification was based primarily on morphology (physical appearance), with a specific focus on reproductive anatomy, the flowers and seeds. If a new plant had flowers that looked like a Lily, it was put in the Lily family.

However, this system has a flaw, the human factor. Relying on visual observation is subjective. Just because two plants look alike does not mean they are closely related. This is often the result of convergent evolution, where unrelated species develop similar traits to survive in similar environments (like how both sharks and dolphins have fins, even though one is a fish and the other a mammal).

When DNA became more interesting than reproductive systems

In the late 20th and early 21st centuries, the field was revolutionized by DNA sequencing and phylogenetics. Instead of just looking at parts of the plant, scientists could now look at the plant’s genetic instruction manual.

This technology definitely shook things up. As our genetic map of the plant kingdom becomes more accurate. Due to this, we also see popular houseplant genera being reorganized. This usually involves:

• Clumping: Moving species from one genus into another genus. For example, the Mother-in-law’s Tongue (previously considered Sansevieria) was moved into Dracaena because DNA showed it was essentially a succulent Dracaena rather than its own genus.

• Splitting: Moving species out of a genus into one or several new ones. For example, many plants in the genus Senecio were split into Curio (like String-of-Pearls), Kleinia, and Caputia.

The Ever-Evolving Family Tree

While it can be frustrating to relearn names for old favorites, these changes ensure our classification system reflects the true evolutionary history of the plant kingdom as we discover it. Science is always evolving as we gradually learn more about how plants truly relate to each other.

So, the next time you see a new name at the garden center, remember it’s just us getting to know the plant’s family tree a little better. If you see an old name on social media or a nursery tag, be kind! It’s hard for everyone, including the pros, to keep up.
And remember, your plant is still just as beautiful and interesting, no matter what it’s called!

A brief selection of new names for old favorites:

• Rosemary, Rosmarinus officinalis → Salvia rosmarinus

• Mother-in-law's tongues, Sansevieria → Dracaena

• Russian Sage, Perovskia atriplicifolia → Salvia yangii

• Lindheimer's beeblossom, Gaura lindheimeri → Oenothera lindheimeri

• String-of-Pearls, Senecio rowleyanus → Curio rowleyanus

• most of the Calathea we're used to grow → Goeppertia

• Fishbone Cactus, Epihyllum anguliger → Disocactus anguliger