Learn the language of plants

A little botanical Latin self-study could make you a better gardener

The plants are trying to tell us something — if only we’d learn their official language, botanical Latin.

“I am the Allium with just one leaf,” says Allium unifolium. (Get it?)

“I amthe juniper that carpets the ground,” says Juniperus horizontalis (whose alternate name, Juniperus prostrata, nails its appearance, too).

And Aster alpinus chimes in:

“My ancestors hailed from above the timber line — you know, like, the Alps. I won’t appreciate some sodden, clayey spot in your garden.”

Not all plant names offer such easy clues about traits like appearance, preferred conditions or place of origin. It’s worth digging deeper, though, and I’m grateful to several formally trained old-school horticulturists, my first garden teachers, who used botanical Latin confidently.

Now, a recent book called “The Gardener’s Botanical: An Encyclopedia of Latin Plant Names” is nudging me to sharpen my skills. The author, Ross Bayton, earned his doctorate in plant taxonomy at the University of Reading and the Royal Botanic Gardens, Kew, in England, and is now the assistant director of the public Heronswood Garden in Kingston, Washington.

Bayton learned his first botanical Latin word around the age of 11, from his mother’s beloved sweet peas, Lathyrus odoratus, a plant she grew every year.

“I realized that odoratus meant fragrant, and then I saw that word on other plant labels in my own garden, like Viola odorata, Galium odoratum,” he recalled. “And that kicked it all off for me.”

In his garden, he then connected the dots of mollis, for soft (Acanthus mollis, Alchemilla mollis), and its opposite, spinosa, for spiny (Acanthus spinosus, Aralia spinosa).

Now they join odoratus among the 5,000-plus entries in his illustrated dictionary.

Our proposal: A little botanical Latin self-study might make better use of some of your garden offseason hours than rewatching that TV series you already rewatched. A plant’s Latin name is the only way to know for certain what you’ll be getting when you buy plants in the spring, as common names vary by region — but you have to know how to decode some of the words.

“Accuracy — knowing a plant’s correct name — is the key to finding out everything about it,” said Bayton, who offers the common name bluebell as one example of inaccuracy’s slippery slope.

Which bluebell? The native Eastern wildflower Mertensia virginica or Hyacinthoides non-scripta, a bulb from Western Europe and England? The Campanula referred to as Scottish bluebell, or the Australian, Texas or California bluebells, each in a different genus?

Unlike common names, which can be shared by multiple plants and vary regionally, the Latin name is universal.

But even when we know the genus, let’s graduate beyond “my hydrangea” to the other word in the Latin binomial, the species name or specific epithet that modifies it.

Let’s get to Hydrangea quercifolia (translation: the hydrangea whose leaves resemble those of an oak, oaks being genus Quercus), helping discern it from Hydrangea paniculata (whose leaves don’t).

“Hydrangeas are a big group, and they don’t all need the same treatment,” Bayton said. “If you want to know how to prune one, there are four distinct ways — so knowing it’s a hydrangea isn’t enough information.”

(Speaking of which, here’s a pop quiz, or a trick question: What’s the common name of the genus Hydrangea? Answer: There isn’t one. “What allows a name to skip over that botanical Latin barrier and not be feared?” Bayton said of the list of plants like this, which includes Magnolia, Rhododendron, Camellia, Iris, Fuchsia and Begonia. “Ahandful of iconic garden plants have names that are easy to pronounce and spell, and are so widely used that they’re devoid of dread.”)

Sometimes, imprecision can be not just inconvenient — the wrong plant ordered, a plant incorrectly pruned — but potentially dangerous, he said. Although Castanea

(the true chestnut) and horse chestnuts (Aesculus) share that one key word in their common names and also some traits (both are deciduous trees bearing spiny fruits), they are not related, and the latter’s fruits, also called buckeyes, are poisonous.

Most Latin names are descriptive — sometimes vividly so. Toxicodendron (the genus of poison ivy, oak and sumac) and Urtica (stinging nettles; Urtica means “to burn”) spell danger: toxicity or the risk of urticaria, a skin rash.

A species name might reveal a slightly less terrifying trait, such as flower color. Yellow may be flavus or luteus, citrinus (lemon-colored) or aureus (gold). Silver is argenteus. Red is rubrum, as in the red maple (Acer rubrum); rosypink, roseus. Blue shades include azureus (sky) and darker caeruleus. Purple is purpureus. White is albus; black, nigrum (black pepper, Piper nigrum).

Native habitats might instead be called out by descriptors like sylvatica (of the woods) or palustris (marshland), maritima (seaside) or aquatica (in water).

Some plants speak of their geographic origins. Various Eastern North American natives bear the epithets canadensis or virginiana. But occasionally this backfires: Scilla peruviana doesn’t hail from Peru, although it did travel from its southwestern European or northwest African homeland on a ship named Peru, Bayton said, confusing the botanist who named it. The rules of botanical nomenclature say the oldest valid species name sticks, so it is peruviana evermore.

There is even the occasional anagram, where an existing genus name is remixed to form a new, botanically related one: Saruma is a cousin of the more familiar Asarum, like the native ground-cover ginger, Asarum canadense.

“Sometime taxonomists are just having fun with us,” Bayton said. “Like the one who named a cactus genus from Argentina Denmoza, because it comes from the province of Mendoza.”