Begonia (Begonia x tuberhybrida pendula 'Illumination Apricot'). Begonias are native to humid subtropical and tropical climates and are often grown indoors. This plant does well on a shady patio. The photo shows one of seven varieties in Proven Winners' Illumination series. The plant family Begoniaceae includes two genera, Begonia, with more than 2,000 species, and Hillebrandia, with one species (sandwicensis). (Courtesy of Tom Karwin)
Editor's note: A version of this column previously appeared in the Sentinel.
Sooner or later, successful gardening will require knowing the names of plants.
Some gardeners are content to refer to their plants casually (“I love that lovely pink rose!”). Others understand that plants have specific scientific names and want to correctly identify them.
Correct identification is important when a gardener needs to know a plant's definitive name to learn information about growing, propagating, its natural habitat, its size at maturity, and so on.
The scientific name of an organism consists of two elements, the genus and the species, which are called the generic name and the specific epithet, respectively.
Today's photo gallery features plants that are currently blooming in my garden. In the captions you'll find the plant's common name and scientific name. Both names are helpful in identifying plants and are also used to identify insects and animals. In today's column, we'll look at both types of plant names.
Plant Name
The plant world is vast, and although parts of it are yet to be discovered, a great many plants have been identified by botanists, taxonomists, or especially knowledgeable plant collectors.
Every identified plant has a unique name that includes its botanical genus and species, called the generic name and the specific name. The combination of the two is called binomial nomenclature.
Genus names are often based on Latin or Greek words that describe the plant. The meanings of both genus names in this example can be found by doing a Google search for the plant by either name.
The second part of the binomial name is the species, which distinguishes the plant from other plants in the same genus. A specific epithet may be given in honor of a person, the plant's natural habitat or characteristics, or other descriptors.
For example, the plant with the common name Pink Mist Bush has the scientific name Syncolostemon obermeyerae. The genus name Syncolostemon is Latin and describes the shape and size of the filaments. The specific name obermeyerae is named after Amelia Obermeyer Mauve, a botanist at the National Herbarium of South Africa who first collected the plant in 1931.
Taxonomists sometimes determine that a particular plant needs a different name as a result of genetic studies, so a plant you know may now have a new, unfamiliar name.
As another example, a friend recently gave me a rooted cutting of a plant that I identified as Hemizygia obermeyerae. Upon investigation, I discovered that it had been renamed Syncolostemon obermeyerae. Recent DNA analysis has determined that the genus Hemizygia is actually the same as the genus Syncolostemon. Because Syncolostemon is an old name, taxonomists chose the old name for both genera.
If two different people discover and name the same plant, the first name is ultimately chosen as the true name.
Common Name
Some generic names are easy to remember. Examples: Chrysanthemum, Dahlia, Geranium, Gladiolus, Iris, Rosa. Other generic names are hard to remember, and when you include species names it gets really difficult. One example is my new plant, Syncholostemon obermeyerae.
Because botanical names can be unwieldy, many plants are given common names. Today's example plant has the common name Pink Mist Bush, a reference to the way the plant produces numerous showy, two-lipped, lavender-pink flowers. Because my new plant has not yet flowered, I'll include a Wikimedia Commons photo of the South African plant in this column.
Because common names are not regulated, a particular plant may have more than one common name, and several plants may have the same or similar common names, so searching using the botanical name is more effective for learning about a particular plant.
Breed name
These two names are sufficient to accurately identify a natural plant. Plant breeders propagate and introduce hybrid plants that have a third name to identify a cultivar (a cultivar). Cultivars can be selected from natural mutations or hybrids, or from human-developed hybrids.
In some cases, the binomial name may include a third name indicating a subspecies (written “subsp.”).
Cultivar names in single quotation marks can be used to identify plants. Cultivars of popular garden plants are often known by just the genus and cultivar name, without the specific epithet (e.g., Rosa 'Fourth of July').
Cultivars based on hybrids may use shorter names, because the correct species name should refer to both parent plants, separated by an “x” (e.g., Species A x Species B). The begonia in today's photo gallery has a longer name indicating that it is derived from a hybrid.
If you need the name of a plant
When you buy a plant for your garden, it should come with a tag that lists its botanical name. This tag is your key to finding out more about the plant in a book or on the internet.
But sometimes you don't know the name of a plant and you need to know what to call it, how to care for it, and where to plant it in your garden.
For example, I recently purchased a small unlabeled plant at the Santa Cruz Garden Exchange, and its leaves look very similar to some geraniums already in my garden, so it could be a plant of that genus, but the flowers are very small, about 1/2 inch in diameter, so they are unlike the other geraniums in my garden.
A quick way to identify a “mystery plant” is to take a snapshot and enter it into a plant identification application on your phone. There are several such applications, including FlowerChecker, LeafSnap Premium by Appixi, Picture This, PlantID by Control, PlantNet, and PlantSnap Pro. These are often available for free (but are ad-supported), but some are available on a subscription basis.
Plant identification can be difficult, especially for rare species, but technology is improving. One option is PlantNet, which has high ratings from rating services. It's available for free from PlantNet.org, the Apple App Store, or Google Play.
Another highly rated app is inNaturalist, also available for free from iNaturalist.org (a non-profit organization), the Apple App Store, or Google Play.
I entered a snapshot of the mystery plant into the PlantNet app, which quickly identified it as a black pelargonium (P. sidoides)—the common name refers to reddish-purple flowers, but the flowers on my specimen, while reddish, are hardly what you'd call “black.”
I submitted the same snapshot to the National Horticultural Society's plant identification forum, and a forum volunteer identified the plant as Pelargonium reniforme subsp. reniforme.
I checked the ID on PlantzAfrica.com, which said, “One cultivar with dark purple flowers is now considered a separate species. Pelargonium sidoides was formerly known as Pelargonium sidaefolium.” So, the people supporting NGA's Plant ID forum were doing a better job than PlantNet.
But I won't ignore this app, it could be a useful resource for you while out walking in the garden.
Enjoy your garden!
Tom Kerwin is past president of the UC Santa Cruz Botanical Garden and Monterey Bay Iris Society, past president and life member of the Monterey Bay Area Cactus and Succulent Society, and a UC Lifetime Master Gardener (certified 1999-2009). He currently serves on the Santa Cruz Hostel Association Board of Directors and is active in the Pacific Horticultural Society. Photos of his gardens can be found at https://www.facebook.com/ongardeningcom-566511763375123/. For gardening instructional information and archives of On Gardening columns, visit ongardening.com to view previous columns and www.santacruzsentinel.com/ to search “Karwin” for recent articles. Please email your comments and questions to gardening@karwin.com.
