Last summer, a humorous conversation with chapter board members led to my writing about plants that come up between the cracks of the sidewalk; members sharing their photos was the impetus for a descriptive blog post about 15 plants. For a refresher, it is at the following link, but first, read on. https://www.stbctmn.org/post/anita-s-blog-miniature-gardens-in-the-cracks-of-the-sidewalk
Just days prior to the City Nature Challenge 2023, and after some rainy days in the Valley, our chapter Webmaster, Joseph Connors, e-mailed me, saying that as he was driving around, he was seeing a lot of stuff growing in cracks. He thought with all the rain, it might be time for another crack article – different time of year, different plant life.
I sent out a plea for chapter members to be on the lookout for sidewalk crack plants as they went about their observations for the annual BioBlitz. Almost before the ink was dry on the e-mail request, chapter members Velma Schmidt from Edinburg, Janice Mingus and Kate Krause, both from the north McAllen area, submitted photos. This post describes those 10 species. I debated starting with either the worst plant or my favorite; taking them alphabetically pushed the worst to the top of the list, pay particular attention to its looks.
Brazilian pepper or Peruvian pepper, Schinus terebinthifolius. This particular species gives me a rat prickle of fear whenever I find it in my yard because I know what can happen if it’s left to its own devices. If you find it less than two feet tall, grab it at the base and pull it out of the soil. If it doesn’t come up, dig it out, or cut it at soil level and paint the stub with a chemical designed to stop plant growth.
Brazilian pepper is high on the Texas invasive list – as a matter of fact, it’s one of the Texas Dirty Dozen invasives. Its worst sin is that the leaves produce a chemical that inhibits germination and growth of other plants, including native species.
Just as horrifying, it produces massive amounts of apparently scrumptious fruit in the winter that birds cannot resist. Inadvertently, our pretty feathered friends help populate the landscape with these trees. Once they establish, the plants “overtop and shade out other vegetation,” according to Richardson, A., King, K. 2011. Plants of Deep South Texas: A Field Guide to the Woody and Flowering Species. Texas A&M University press, College Station, page 67.
I wrote a (lengthy) blog post about Brazilian pepper in 2017, at the following link: But continue on with this new missive for now. https://rgvctmn.org/blog/anitas-blog-gazilian-brazilian-peppertrees/
Common ragweed, Ambrosia artemisiifolia. I’d remove this plant post haste if I found it coming up between the cracks in a sidewalk. According to the Lady Bird Johnson plant database at www.wildflower.org, common ragweed, not goldenrod, is the cause of hay fever. Common ragweed is native to much of North America. The plants can grow to five feet tall but probably don’t, here.
Common ragweed is wind pollinated, so it's really easily and happily reproducing in the Valley; apparently, the drab flowers don’t attract insects. If it's not busy enough pollinating in the wind, the plant also propagates underground by rhizomes. If you let these plants mature, songbirds and game birds will love eating the seeds, but that will only mean more plants. Rabbits and grasshoppers are said to eat the leaves, but we have other more valuable and kinder plants for birds and wildlife, like the next plant.
Common sunflower, Helianthus annuus. If Brazilian pepper is the worst, our native sunflower is the best, going so far as being able to help heal the earth of nuclear radiation like after a dastardly tsunami destroyed reactors in the Fukushima nuclear power plant in Japan.
I nearly always put in a plug for sunflowers whenever I give a presentation about native plants or gardening for critters and pollinators.
I can’t say enough for promoting sunflowers, with which nature freely dots our countryside – well, except perhaps you might not want to let it mature in the crack of a sidewalk; they don’t stay cute and small and can quickly get out of hand. Their stalk can get larger than an inch in diameter, so thank it and gently tug it out. Sadly, they don’t do well when replanted, but you’re bound to have others coming up in better positions throughout your yard.
Here are the points I share during a presentation:
• They are likely to be blooming all year long
• Pollen and nectar for butterflies, bees, beetles, lacewings, flies and moths
• Seeds for squirrels, mice, beetles, Rio Grande turkeys, bobwhite quail
and other birds
• Flowers and plants good source of protein and fat for deer
• Leaves consumed by chachalacas and rabbits
• Flowers and stalks food for rabbits when they can reach them
• Seeds that have fallen to the ground, food for rabbits
• Larval host to painted lady, American lady, bordered patch and
silvery checkerspot butterflies
• Dead stalks left standing provide homes for some species of
• Root base helps hold soil during windy weather
• Spent sunflowers, mowed down and mulched add nutrients and
microorganisms to the soil
Horseweed, Erigeron canadensis. I find about one of these plants each year. I keep it just to see what it will do, and it doesn’t do anything except continue to grow taller. It’s easy enough to pull out of the soil when I'm bored with it. According to references, horseweed often grows as a single vertical shoot up to seven feet tall and has a large panicle of flowers on top. Sometimes it will branch low near the soil, but rarely branches above. The leaves are dark green, hairy with short stiff hairs and without petioles (the stalk that attaches the leaf blade to the stem).
It is an annual, blooms in summer, and depending which state or country you’re in, it is adaptable, prolific and possibly invasive. It’s native to North America and has been widely introduced to other parts of the globe. In Texas, it’s not exactly cherished; it vies for water in agricultural fields.
I think it might be best to pull this one up no matter where you find it. On a good note, its flowers are visited by insects that drink nectar, including wasps and flies. The leaves apparently have bitter-tasting chemicals, so they are not useful to wildlife. One source, a post called “The Humane Gardener,” which appears to be about somewhere in New England, touted it to be an important nectar source for monarch butterflies during fall migrations. I think the keynote there is that it is written about the species in a habitat quite unlike ours. Our Lower Rio Grande Valley fall blooming plants can provide adequate nectar for monarchs and other butterflies; therefore, this is not a keeper.
Jamaicanweed, Nama jamaicensis, also called fiddleleaf Nama. This is a sweet little groundcover that spreads in a rosette of small, shapely grey-green hairy leaves. It has tiny white, five-petaled flowers that look like a miniature cup, if you can see them at all. It is an annual prostrate plant in the waterleaf family, native in southeastern United States, the West Indies, Mexico, Central America and South America. I regard it as a temporary, rather benign groundcover that doesn’t seem to hang around all year but can be found in late winter and spring in subsequent years. As for a sidewalk crack plant, I’d leave it just to note its progress and have a pleasant plant decorating the hard grey substrate. I’ve not found where it is useful to wildlife although I’ve several times photographed dragonflies resting on it.
Mexican fan palm, Washingtonia robusta. Look at the skyline anywhere around you and you’ll see this plant. They are not native to the Rio Grande Valley, but they make a great habitat for bats and other birds, insects, beetles and cockroaches – the more trees outside that house roaches, the less roaches in the house, right?
Don’t let an upstart linger long in the cracks of a sidewalk, though. Even tiny ones, with just one leaf blade coming up, are not easy to pull up. Chop them off with a string weeder if they won’t pluck up. At certain times of the year these palms spill their seeds like a burst bag of peas. The seeds have a high rate of germination. I have a Master Gardener friend who tells people who think they can’t get anything to grow to “plant a few palm seeds.”
Mexican holdback, Erythrostemon mexicanus. Locally, we call it Mexican Caesalpinia; iNaturalist.org uses the Mexican holdback moniker. I’d quickly remove this from a sidewalk crack and from around the foundation of any building.
The tree is in the legume family and can grow to 19 feet tall, but generally is a few feet shorter. Once the little saplings get beyond about 10 inches tall, they are impossible to pull out of the ground by hand. Weed whacking might not take care of errant sidewalk specimens. It may have to be clipped, and it wouldn’t be amiss to paint it with a tree and stump remover. I once dug out an 18-inch-tall upstart and dug deeper than that to get all the root out. New growth quickly establishes a single, long, straight root headed for China.
I purchased a small Caesalpinia tree when I was first a Texas Master Naturalist in 2013, because a birding enthusiast said it was a must-have tree to attract birds. I’d like to voice a caution here, especially to our new chapter graduates. Be careful who you talk to – let me rephrase, don’t take advice without a little research of your own. Caesalpinia trees are fast-growing and entertaining. They create a different look each season. Beautiful canary yellow blooms grace the branches four times a year; they attract only Mexican carpenter bees, despite what birders may say. Don’t get me wrong, the bees are big, beautiful and iridescent purple in the morning sunlight; they don’t bombard you while you’re taking their photo. After the blooms, legume-family type pods (hundreds) turn a golden tan and then suddenly twist apart, slinging numerous, viable seeds as far as they can. This is why I have more than a few Caesalpinia trees accompanying the original.
Mexican prickly poppies, Genus Argemone. Prickly poppies are some of my favorite spring plants, especially the Mexican prickly poppies whose blooms are a lively deep yellow. The seeds are eaten by bobwhite quail and mourning doves. The white blooming species, which are more prevalent, enjoy a large variety of visitors to the rich pollen, like speckled garden beetles, big katydids, flies, bees and other bugs. I’d keep any coming up between the cracks of a sidewalk or anywhere you find them, only because prickly poppy plants are becoming fewer and fewer each year. I’ve not had the opportunity to observe and photograph the Mexican yellow poppies. Nor have I been successful in germinating seeds of any species of prickly poppies.
If it’s not in the way in a sidewalk crack, I’d say, leave it to mature, bloom and go to seed; try to collect the seeds and scatter them in a better spot, hopefully to grow and bloom in future years. The leaves are beautiful to look at with their bright white rachis and grey-green outer leaf, but sharp as daggers at every point, so the sidewalk version might become annoying while you baby it to fruition.
Tiny Tim, Dogweed, Bristleleaf pricklyleaf (iNat), Thymophylla tenuiloba. These bright yellow bundles of daisy-like blooms atop soft, fringy leaves are always a delight to see as winter wanes. They are native to south central Texas and northern Mexico. Blooming declines in hot humid climates; they self-sow in good conditions. As depicted in the photograph, it looks to be an ideal plant, with absolutely no evil intent, to jazz up an ordinary sidewalk. Not every garden will be lucky to have this polite, compact mound that seems to top out at less than 10 inches tall. It prefers full sun on well-drained sandy soils like sandy loam and caliche. It is listed as a butterfly nectar plant. Left in a sidewalk garden, it will be easy to monitor and gather seeds after they have dried on the plants.
Whitemouth Dayflower Commelina erecta, also called dayflower and widow’s tears. The stems are jointed and lanky; they can reach up to three feet long and will be upright only if supported by other plants. The flower is about one inch across. Each bloom lives only for a day, but the plant will continue to push out blooms during all seasons. I’ve seen various insects flit about on these blooms, for what that’s worth, flit being the operative word. I’m so not a fan of this species, primarily because if you have one, you have hundreds. It cannot be tugged out of the ground, but rather requires digging up. It has been described as having tenacious, fleshy roots. More accurately, the roots are octopus-like, five inches long and cling frantically to the soil.
It pays to pay attention to the miniature gardens of your sidewalks, like South Texas Border Chapter Texas Master Naturalists Velma Schmidt, Janice Mingus and Kate Krause did for this article. Thank you for generously sharing your photographs!