Awkward Botanical Sketches #4: Boise Goathead Fest Edition

Covid-19 be damned, Boise Goathead Fest is happening in 2020. However, since we’re in the middle of a pandemic and the number of infections in Idaho have been far greater than we’d like them to be, this beloved, summertime event (now in its third year) is going to look quite a bit different this time around. No giant bicycle parade snaking through downtown Boise, no big gathering in the park to celebrate bicycles and recogonize all who helped pull goatheads across the Treasure Valley, and (I have to assume) no bike sumo. But we’re still going to decorate our bikes and ourselves like a noxious weed and go for a bike ride, and even though we won’t all be able to gather together in one spot, the sentiment will undoubtedly be the same.

I’m a big fan of the Goathead Fest, and not simply because I love bicycles and bike-culture. In fact, it’s mostly because a plant – while despised by all who ride bikes in this area – takes centerstage in the celebration. Not too many plants get this kind of attention. And sure, it may only find itself in the spotlight because of its bad behavior, but at least it has people paying more mind to green things.

In anticipation of this year’s Goathead Fest, I decided to make a few attempts at drawing Tribulus terrestris. Goathead art has played a big part in the festivities since year one, and this year is no exception. In a normal year, all of the artwork would be displayed together in Cecil D. Andrus Park. This year, pieces of art will be displayed around town for us all to happen upon as we embark on our socially distanced bike rides. However, you won’t see any of my artwork out there (for good reason). Maybe someday (one can dream, I guess). Until then, I’ll include a few of my awkward attempts below.

the flower of Tribulus terrestris

an attempt to color the flower of Tribulus terrestris

goathead nutlets #1

goathead nutlets #2

Tribulus terrestris leaf rubbing

Goathead Monster #1

Goathead Monster #2

More Awkward Botanical Sketches: 

How to Identify Puncture Vine (a.k.a. the Goathead Monster)

This post originally appeared on Idaho Botanical Garden’s blog. With the first annual Boise Goathead Fest fast approaching, the purpose of this post is to help people in the Treasure Valley identify goatheads so that they can collect them for drink tokens to use at the event. I’m reposting it here in hopes that people around the globe who are tormented by goatheads might benefit from it. All photos in this post were taken by Anna Lindquist.

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If you have spent much time on a bicycle in Boise, chances are you have been the victim of a goathead-induced flat tire. You probably even got a good look at the spiky nutlet as you went to remove it from your tire. But where did the culprit come from? No doubt, it came from a plant. But which one?

This is particularly useful to know right now because the first annual Boise Goathead Fest is coming up, and if you manage to fill a garbage bag full of these noxious weeds before the end of July, you will earn yourself a drink token. Fortunately, this plant is fairly easy to identify; however, there are a few look-a-likes, so it is important to familiarize yourself with the plant in question so you can be sure you are pulling the right one.

puncture vine (Tribulus terrestris)

Puncture vine, also known as goathead or Tribulus terrestris, is a warm season annual that is native to the Mediterranean region of southern Europe. It was introduced to North America unintentionally by early European settlers when the plant’s blasted burs snuck their way across the ocean in sheep wool. Since then, puncture vine has spread across the continent prolifically thanks to the hitchhiking prowess of its seeds.

Behold, the infamous Goathead Monster.

Puncture vine has a prostrate habit, meaning that its branches lie flat on the ground, spreading outward from a central location. It grows upward only when it is being shaded or crowded out. Its leaves are divided into several tiny leaflets, and its flowers are small and bright yellow with five petals. It is an otherwise pretty plant were it not for the threatening, jagged fruits that follow the flowers. As these fruits dry, they dislodge from the plant, split into five pieces, and lay in wait to puncture your tire, work their way into the bottom of your shoe or the foot of an animal, or latch onto some errant fur.

puncture vine (Tribulus terrestris)

Depending on the conditions, puncture vine either remains fairly small or spreads as much as six feet wide. Fruits start forming shortly after flowering, and seeds ripen soon after that, so if the plant isn’t removed quickly – nutlets and all – future populations are guaranteed. Luckily the plants are fairly easy to remove. Unless the ground is particularly compact, they pull up easily, and if they break off at the root, they generally don’t sprout back.

Virtually any plant that has a prostrate growth habit and is actively growing in the summer could, at first glance, be mistaken for puncture vine. Closer inspection will help confirm the plant’s true identity. Two plants that might confuse you are purslane and spotted spurge. Both of these species can be found growing in full sun in disturbed or neglected sites in close company with puncture vine.

Purslane has tiny, yellow, five-petaled flowers similar to puncture vine; however, its leaves are glossy and succulent-like and its stems and leaves often have a red to purple hue to them. Purslane seeds are miniscule, and while the plant can be a nuisance in a garden bed, it poses no threat to bicycles or wildlife.

purslane (Portulaca oleracea)

Spotted spurge, also known as prostrate spurge, can be quickly distinguished by the milky sap that oozes from its broken stems. Its leaves are generally reddish purple on the undersides with a purple spot on top. Its flowers are minute and its seeds even smaller. Because its sap contains latex and other chemicals, it can irritate the skin and poison creatures that dare eat it.

spotted spurge (Euphorbia maculata)

Both of these plants are introduced, weedy species, so even if they won’t count towards your drink token, it still doesn’t hurt to pull them. Puncture vine, however, is included on Idaho’s noxious weed list, which means it is particularly problematic. So take this opportunity to pull as many as you can, and hopefully we can put a sizeable dent in the population of a plant that has tormented Boise bicyclists for far too long.

See Also: Plant vs. Bike