Plant Identification When Apps Fail: Strategies for Untrained Botanists and Impatient Plant Lovers

Southwest Yard & Garden

By Marisa Thompson

Whole-plant and close-up photos taken in October 2021 in Corrales, New Mexico and submitted to the NMSU Cooperative Extension Service for help with plant identification. Photo credits Roger L.

Question: Last October, we saw a beautiful plant blooming in an open lot in Corrales. Any ideas what it might be? The flowers in the second photo dry to become delicate triangular structures about 3/4 inch diameter in the last photo. I have a few seeds and am considering propagation.

- Roger L., Corrales

Answer: Firstly, thank you for taking the time to confirm that the plant you saw is one we want to grow in New Mexico before propagating it from the seeds you saved. Lots of weedy species have remarkably beautiful flowers—I’m looking at you field bindweed (Convolvulus arvensis) and puncturevine (Tribulus terrestris, aka goatheads). We’d be in even bigger trouble if we started saving those seeds and intentionally spreading them around.

When I looked at your photos, I thought the plant looked familiar, but I couldn’t quite place it. The tightly packed balls of pink, petal-like structures look a little like the pom-pom flowerheads of a hydrangea. Note: Hydrangeas are not native to our region and are generally not recommended for New Mexico gardens, partly because most varieties are not cold hardy here, and partly because they grow better in acidic soils. For more details on why hydrangeas are a toughie in the Land of Enchantment, find my esteemed predecessor Dr. Curtis Smith’s 2006 article by searching “hydrangeas” in the column archives (https://aces.nmsu.edu/ces/yard/search).

Another plant that came to mind when looking at those dried, papery forms was bougainvillea. The bright colors on bougainvilleas are not flowers, they’re modified leaves (aka bracts) that hold their color much longer than most flower petals. In the photos, the shape looked like the seeds (more correctly, dried fruits) of fourwing saltbush (Atriplex canescens), but I’ve never seen these shrubs with hyper-intense pink colors.

None of the plants swimming in my head was a likely match for the plant in the photos, so I pulled out my phone to try my three favorite plant identification apps. I’ve written about the pros and cons of using these apps before; find that September 2018 column at https://nmsudesertblooms.blogspot.com/2018/09/theres-app-for-that-identifying-plants.html.

This time, however, all three of my trusted apps were only demonstrating the cons of relying on smartphone technology. First, my favorite favorite: iNaturalist. After adding all three photos and selecting the Corrales area on their location map, the result was “We’re not confident enough to make a recommendation,” and they didn’t even list a few to try, like normal. Next, Pl@ntNet offered thirty-plus possibilities, but each seemed to be a worse guess than the one before—smoketree, tropical milkweed, celosia, red amaranth, coastal indigo. Finally, I tried PictureThis, which quickly reported that they’d found a match: crown of thorns (Euphorbia milii). No disrespect to crown of thorns (I personally own several and they’re troopers), but it’s a tropical houseplant, native to Madagascar, not something we’d find outdoors in New Mexico.

I was perplexed. These three apps don’t always work well, but usually at least one leads me in a direction that ends well. I’d expect this result if the photos were terrible (blurry, too busy, too far away, etc.), but this time, aside from a detailed leaf pic, the photos were exactly what we hope for: one of the entire plant, one close-up of the flower-like structure, and another of dried petal-like seed structures. This should have been a clue to someone like me.

When the apps failed, I was about to start worrying, but I remembered that there are wonderful Facebook groups to try as well.

Along with the October date and approximate location, I posted the photos to the local Facebook group “Native Plants of New Mexico,” which has almost 13,000 members. Within minutes, one of the amazing admins, Karl Horak, commented, “Tripterocalyx micranthus in fruit?” Commonly called pink sandpuffs and small-flowered sand verbena, this turned out to be the likely identification, and indeed a plant that is indigenous from New Mexico to California and up into southern Canada.

I appreciate several aspects of Horak’s brief comment. For one, including the official botanical name was helpful because common names are more easily mixed up and can be misleading. The question mark at the end of the comment let group members know he wasn’t 100% sure, and, importantly, this acted as an invitation for other experts and people who have experience with this plant to speak up, either in confirmation or with a contrasting opinion, thereby encouraging discussion. And by adding “in fruit,” Horak helped us home in on a key aspect: the pink structures in the photos are not clusters of petals, they are the dried fruits that formed long after the flowers disappeared last summer.

The clue was that the photos were taken in October, long after we expect most plants to be flowering. It wasn’t that I completely missed this detail, it’s more that I didn’t take the time to think about the photographed plant structures in a seasonal context. This plant’s flowers, born in May and June (later in cooler climates), are tiny, mostly white with red stems, and trumpet-shaped. I wonder if any of my apps would have yielded a correct answer if I had included flower photos. In retrospect, leaf pictures may have helped, too.

Sure enough, a fun discussion bloomed in the comments of my Facebook post as others chimed in: “Right on the money!” “They grow wild in Rio Rancho,” “They grow wild on the ditches out here in Corrales,” “... tough to propagate [in captivity], it’s easier to start by just tossing seeds in the native soil,” and “…they self-sow and come back every year. Very beautiful.”

Others commented with alternative, but closely related, suggestions like winged sandpuffs (Tripterocalyx carneus) or Wooton's sandpuffs (Tripterocalyx wootonii, perhaps a variety of T. carneus). Either way, we’ve determined that this lovely annual plant is a sand verbena in the four o’clock family that is highly regarded and recommended in sandy locations throughout most of the state. Although, it may be difficult to find in a nursery. Readers who come across them are encouraged to share photos. How long into the winter does that bright pink color last?

Small-flowered sand-verbena (Tripterocalyx micranthus) in bloom (white, trumpet-shaped flowers) and with fruit (pink-orange, papery structures) on 17 June 2017. Photo credit Wikimedia Commons, Great Sand Dunes National Park and Preserve, Patrick Myers. https://commons.wikimedia.org/wiki/File:Small-Flowered_Sand_Verbena,_Great_Sand_Dunes.jpg

 

 

 

 

For more gardening information, visit the NMSU Extension Urban Horticulture page at http://desertblooms.nmsu.edu/ and the NMSU Horticulture Publications page at http://aces.nmsu.edu/pubs/_h/. Find your local Cooperative Extension Office at https://aces.nmsu.edu/county/.

 

Marisa Y. Thompson, Ph.D., is the Extension Urban Horticulture Specialist in the Department of Extension Plant Sciences and is based at the New Mexico State University Agricultural Science Center at Los Lunas.