Weeds of Boise: Railroad Tracks Between Kootenai Street and Overland Road

Walking along railroad tracks is a pretty cool feeling. It’s also a good place to look for weeds. Active railroad tracks are managed for optimum visibility and fire prevention, which means that trees and shrubs near the tracks are removed creating plenty of open space on either side. Open areas in full sun are ideal places for a wide variety of weed species to grow. Trains passing through can also be sources or dispersal agents of seeds, so there’s a chance that you may see things growing alongside railroad tracks that you don’t often see elsewhere. All this means that railroad tracks in urban areas are great locations to familiarize yourself with your city’s wild urban flora.

I visited a small section of railroad tracks between Kootenai Street and Overland Road in Boise. At one point, this was a pretty active railroad. Passenger trains once moved along these tracks, and the Boise Depot, which is less than a mile from this location, was one of several stops between Portland, OR and Salt Lake City, UT. Unfortunately, those services ended in 1997 and have yet to resume, despite continued support for bringing passenger rail back to the region. Still, freight trains pass by with some frequency.

Managing weeds along railroad tracks in urban areas can be tricky. There is little else in the way of vegetation to compete with the weeds. The tracks are also adjacent to parks, homes, schools, gardens, and other locations that make herbicide applications complicated. The species of weeds can also vary widely from one mile to the next, so management decisions must also vary. It’s especially important that the ballast directly beneath and on either side of the tracks is kept weed free in order to prevent fires and improve visibility. All of this and more makes weed control along railroad tracks one of the most challenging jobs around. Luckily, for someone that likes to look at weeds, it means there will always be interesting things to see near the tracks, including for example this colony of harvester ants that I came across while identifying weeds. I was happy to see that they were collecting the samaras of Siberian elm (Ulmus pumila), one of several weedy trees in the Treasure Valley.

What follows are a few images of some of the weeds I encountered along the railroad tracks between Kootenai Street and Overland Road, as well as a list of the weeds I was able to identify. The list will grow as I identify the mystery weeds and encounter others that I missed, as is the case with all posts in the Weeds of Boise series.

Virginia creeper (Parthenocissus quinquefolia)
blue mustard (Chorispora tenella)
cleavers (Galium aparine)
whitetop (Lepidium sp.)
Himalayan blackberry (Rubus bifrons)
bush honeysuckle (Lonicera sp.)
Siberian elm (Ulmus pumila)
English ivy (Hedera helix)
kochia seedlings (Bassia scoparia)
  • Arctium minus (common burdock)
  • Bassia scoparia (kochia)
  • Bromus diandrus (ripgut brome)
  • Bromus tectorum (cheatgrass)
  • Chorispora tenella (blue mustard)
  • Conium maculatum (poison hemlock)
  • Convolvulus arvensis (field bindweed)
  • Cirsium arvense (creeping thistle)
  • Dactylis glomerata (orchardgrass)
  • Descurainia sophia (flixweed)
  • Elaeagnus angustifolia (Russian olive)
  • Epilobium ciliatum (northern willowherb)
  • Equisetum sp. (horsetail)
  • Erodium cicutarium (redstem filaree)
  • Galium aparine (cleavers)
  • Hedera helix (English ivy)
  • Hordeum murinum (wild barley)
  • Lactuca serriola (prickly lettuce)
  • Lepidium sp. (whitetop)
  • Lonicera sp. (bush honeysuckle)
  • Parthenocissus quinquefolia (Virginia creeper)
  • Poa bulbosa (bulbous bluegrass)
  • Poa pratensis (Kentucky bluegrass)
  • Rubus bifrons (Himalayan blackberry)
  • Rumex crispus (curly dock)
  • Secale cereale (feral rye)
  • Taraxacum officinale (dandelion)
  • Ulmus pumila (Siberian elm)

Do you live near railroad tracks? What weeds are growing there, and do you feel as cool as I do when you walk the tracks?

The Weeds in Your Bird Seed

With February comes the return of the Great Backyard Bird Count, a weekend-long, worldwide, bird counting event that Sierra and I have enjoyed participating in for the past few years. While you can choose to count birds anywhere birds are found, part of the appeal of the event is that it can be done from the comfort of one’s own home simply by watching for birds to appear right outside the window. If there are bird feeders in your yard, your chances of seeing birds are obviously improved. Watch for at least fifteen minutes, record the number and species of birds you see, then report your sightings online. It’s for science!

Feeding and watching birds are popular activities. In the United States alone, as many as 57 million households put out food for birds, spending more than $4 billion annually to do so. While there are a variety of things one can purchase to feed birds – suet, berries, mealworms, etc. – the bulk of that money is likely spent on bags of bird seed (also referred to as bird feed). Bird seed is a relatively cheap and easy way to feed a wide variety of birds. Unfortunately, it’s also a great way to introduce new weeds to your yard.

Bird seed contaminated with noxious weed seeds is not a new problem. It has been a concern for decades, and some countries have taken regulatory steps to address the issue. In the United States, however, there are no governmental regulations that address weed seed contamination in bird seed.  With this thought in mind, researchers at the University of Missouri screened a large sampling of bird seed mixes to determine the number and species of weed seeds they harbored, as well as their viability and herbicide resistance. Their results were published last year in Invasive Plant Science and Management.

The researchers examined 98 different bird seed mixes purchased from retail locations in states across the eastern half of the U.S. The seeds of 29 weed species were recovered from the bags, including at least eight species of grasses and several annual and perennial broadleaf weeds. 96% of the mixes contained one or more species of Amaranthus, including Palmer’s amaranth (Amaranthus palmeri), which was found in 27 mixes and which the researchers refer to as “the most troublesome weed species in agroecosystems today.” About 19% of amaranth seeds recovered germinated readily, and five of the seed mixes contained A. tuberculatus and A. palmeri seeds that, once grown out, were found to be resistant to glyphosate, the active ingredient in a commonly used herbicide.

Redroot pigweed (Amaranthus retroflexus) is one of several weedy amaranth species commonly found in bird seed mixes (illustration credit: wikimedia commons)

The seeds of grass weeds were found in 76% of the bird seed mixes and included three species of foxtail (Setaria spp.), as well as other common grasses like large crabgrass (Digitaria sanguinalis) and barnyardgrass (Echinochloa crus-galli). Bird seed ingredients that seemed to favor grass seed contamination included wheat, grain sorghum, and proso millet, three crops that are also in the grass family. No surprise, as grass weeds are difficult to control in crop fields when the crop being grown is also a grass.

After amaranths and grasses, ragweed (Ambrosia artemisiifolia) was the third most common weed found in the mixes. This was a troubling discovery since populations of this species have shown resistance to a number of different herbicides. Moving ragweed to new locations via bird seed could mean that the genes that give ragweed its herbicide resistance can also be moved to new locations. Kochia (Bassia scoparia), another weed on the Weed Science Society of America’s list of top ten most troublesome weeds, was also found in certain bird seed mixes, particularly when safflower was an ingredient in the feed.

A similar study carried out several years earlier at Oregon State University found the seeds of more than fifty different weed species in ten brands of bird feed commonly sold at retail stores. Ten of the weeds recovered from the mixes are on Oregon’s noxious weed list. Both studies demonstrate how bird seed can be a vector for spreading weed seeds – and even new weed species and herbicide-resistant genes – to new locations. Weeds found sprouting below bird feeders can then potentially be moved beyond the feeders by wind and other dispersal agents. Weed seeds might also be moved to new locations inside the stomachs of birds.

Addressing this issue can be tackled from several different angles. Growers and processors can improve their management of weed species in the fields where bird seed is grown and do a better job at removing weed seeds from the mixes after they are harvested. Government regulations can be put in place that restrict the type and quantity of weed seeds allowed in bird feed. Further processing of ingredients such as chopping or shelling seeds or baking seed mixes can help reduce the presence and viability of weed seeds.

Processed bird feed like suet is less likely to harbor viable weed seeds (photo credit: wikimedia commons)

Consumers can help by choosing bird feed that is processed or seedless like sunflower hearts, dried fruit, peanuts, suet cakes, and mealworms, and can avoid seed mixes with a large percentage of filler ingredients like milo, red millet, and flax. Attaching trays below feeders can help collect fallen seeds before they reach the ground. Bird seed can also be avoided all together, and feeding birds can instead be done by intentionally growing plants in your yard that produce food for birds. By including bird-friendly plants in your yard, you will also have a better chance of seeing a wide variety of birds during the Great Backyard Bird Count.

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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: 

Dispersal by Bulbils – A Bulbous Bluegrass Story

The main way that a plant gets from place to place is in the form of a seed. As seeds, plants have the ability to travel miles from home, especially with the assistance of outside forces like wind, water, and animals. They could also simply drop to the ground at the base of their parent plant and stay there. The possibilities are endless, really.

But what about plants that don’t even bother making seeds? How do they get around? In the case of bulbous bluegrass, miniature bulbs produced in place of flowers function exactly like seeds. They are formed in the same location as seeds, reach maturity and drop from the plant just like seed-bearing fruits, and are then dispersed in the same ways that seeds are. They even experience a period of dormancy similar to seeds, in that they lie in wait for months or years until the right environmental conditions “tell” them to sprout. And so, bulbils are basically seeds, but different.

bulbous bluegrass (Poa bulbosa)

Bulbous bluegrass (Poa bulbosa) is a Eurasian native but is widely distributed outside of its native range having been repeatedly spread around by humans both intentionally and accidentally. It’s a short-lived, perennial grass that can reach up to 2 feet tall but is often considerably shorter. Its leaves are similar to other bluegrasses – narrow, flat or slightly rolled, with boat-shaped tips and membranous ligules – yet the plants are easy to distinguish thanks to their bulbous bases and the bulbils that form in their flower heads. Their bulbous bases are actually true bulbs, and bulbous bluegrass is said to be the only grass species that has this trait. Just like other bulb-producing plants, the production of these basal bulbs is one way that bulbous bluegrass propagates itself.

basal bulbs of bulbous bluegrass

Bulbous bluegrass is also propagated by seeds and bulbils. Seeds form, like any other plant species, in the ovary of a pollinated flower. But sometimes bulbous bluegrass doesn’t make flowers, and instead modifies its flower parts to form bulbils in their place. Bulbils are essentially tiny, immature plants that, once separated from their parent plant, can form roots and grow into a full size plant. The drawback is that, unlike with most seeds, no sexual recombination has occurred, and so bulbils are essentially clones of a single parent.

The bulbils of bulbous bluegrass sit atop the glumes (bracts) of a spikelet, which would otherwise consist of multiple florets. They have dark purple bases and long, slender, grass-like tips. Bulbils are a type of pseudovivipary, in that they are little plantlets attached to a parent plant. True vivipary occurs when a seed germinates inside of a fruit while still attached to its parent.

Like seeds, bulbils are small packets of starch and fat, and so they are sought ought by small mammals and birds as a source of food. Ants and small rodents are said to collect and cache the bulbils, which is one way they get dispersed. Otherwise, the bulbils rely mostly on wind to get around. They then lie dormant for as long as 2 or 3 years, awaiting the ideal time to take root.

bulbils of bulbous bluegrass

Bulbous bluegrass was accidentally brought to North America as a contaminant in alfalfa and clover seed. It was also intentionally planted as early as 1907 and has been evaluated repeatedly by the USDA and other organizations for use as a forage crop or turfgrass. It has been used in restoration to stabilize soils and reduce erosion. Despite numerous trials, it has consistently underperformed mainly due to its short growth cycle and long dormancy period. It is one of the first grasses to green up in the spring, but by the start of summer it has often gone completely dormant, limiting its value as forage and making for a pretty pathetic turfgrass. Otherwise, it’s pretty good at propagating itself and persisting in locations where it hasn’t been invited and is now mostly considered a weed – a noxious one at that according to some states. Due to its preference for dry climates, it is found most commonly in western North America.

In its native range, bulbous bluegrass frequently reproduces sexually. In North America, however, sexual reproduction is rare, and bulbils are the most common method of reproduction. Prolific asexual reproduction suggests that bulbous bluegress populations in North America should have low genetic diversity. Researchers set out to examine this by comparing populations found in Washington, Oregon, and Idaho. Their results, published in Northwest Science (1997), showed a surprising amount of genetic variation within and among populations. They concluded that multiple introductions, some sexual reproduction, and the autopolyploidy nature of the species help explain this high level of diversity.

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Interested in learning more about how plants get around? Check out the first issue of our new zine Dispersal Stories.

From Cut Flower to Noxious Weed – The Story of Baby’s Breath

One of the most ubiquitous plants in cut flower arrangements hails from the steppes of Turkey and neighboring countries in Europe and Asia. It’s a perennial plant with a deep taproot and a globe-shaped, multi-branched inflorescence loaded with tiny white flowers. In full bloom it looks like a small cloud hovering above the ground. It’s airy appearance earns it the common name baby’s breath, and the attractive and durable nature of its flowers and flower stalks, both fresh and dried, have made it a staple in the floral industry. Sadly, additional traits have led to it becoming a troublesome weed outside of its native range.

baby’s breath (Gypsophila paniculata) via wikimedia commons

Gypsophila paniculata is in the family Caryophyllaceae – sharing this distinction with other cut flowers like carnations and pinks, as well as other weeds like chickweed and soapwort. At maturity and in full bloom, baby’s breath might reach three to four feet tall; however, its thick taproot extends deep into the ground as much as four times its height. Its leaves are unremarkable and sparse, found mostly towards the base of the plant and sometimes with a blue or purplish hue. The flowers are numerous and small, have a sweet scent to them (though not appreciated by everyone), and are pure white (sometimes light purple or pink).

Each flower produces just a few seeds that are black, kidney-shaped, and minuscule. Many of them drop from their fruits and land near their parent plant, but some are retained within their little capsules as the flower stalk dries and becomes brittle. Eventually a stiff breeze knocks the entire inflorescence loose and sends it tumbling across the ground. Its rounded shape makes it an effective tumbleweed, as the remaining seeds are shaken free and scattered far and wide.

baby’s breath flowers close up (via wikimedia commons)

Being a tumbleweed gives it an advantage when it comes to dispersing itself and establishing in new locations, but this is not the only trait that makes baby’s breath a successful weed. Its substantial taproot, tolerance to drought and a variety of soil conditions, and proclivity to grow along roadsides, in ditches, and abandoned fields also make it a formidable opponent. Mowing the plant down does little to stop it, as it grows right back from the crown. Best bets for control are repeated chemical treatments or digging out the top portion of the taproots. Luckily its seeds are fairly short-lived in the soil, so vigilant removal of seedlings and not allowing the plant to reproduce can help keep it in check. Baby’s breath doesn’t persist in regularly disturbed soil, so it’s generally not a problem in locations that are often cultivated like agricultural fields and gardens.

The first introductions of baby’s breath to North America occurred in the 1800’s. It was planted as an ornamental, but it wasn’t long before reports of its weedy nature were being made. One source lists Manitoba in 1887 as the location and year of the first report. It is now found growing wild across North America and is featured in the noxious weed lists in a few states, including Washington and California. It has been a particular problem on sand dunes in northwest Michigan, where it has been so successful in establishing itself that surveys have reported that 80% of all vegetation in certain areas is composed of baby’s breath.

baby’s breath in the wild (via wikimedia commons)

Invading sand dune habitats is particularly problematic because extensive stands of such a deep-rooted plant can over-stabilize the soil in an ecosystem adapted to regular wind disturbance. Plants native to the sand dunes can be negatively affected by the lack of soil movement. One species of particular concern is Pitcher’s thistle (Cirsium pitcheri), a federally threatened plant native to sand dunes along the upper Great Lakes. Much of the research on the invasive nature of baby’s breath and its removal comes from research being done in this region.

Among numerous concerns that invasive plants raise are the affects they can have on pollinator activity. Will introduced plants draw pollinators away from native plants or in some other way limit their reproductive success? Or might they help increase the number of pollinators in the area, which in turn could benefit native plants (something known as the magnet species effect)? The flowers of baby’s breath rarely self-pollinate; they require insect visitors to help move their pollen and are highly attractive to pollinating insects. A study published in the International Journal of Plant Sciences found that sand dune sites invaded by baby’s breath attracted significantly more pollinators compared to uninvaded sites, yet this did not result in more pollinator visits to Pitcher’s thistle. According to the researchers, “a reduction in pollinator visitation does not directly translate to a reduction in reproductive success,” but the findings are still a concern when it comes to the future of this threatened thistle.

Perhaps it’s no surprise that a plant commonly found in flower arrangements is also an invasive species, as so many of the plants we’ve grown for our own pleasure or use have gone on to cause problems in areas where they’ve been introduced. However, could the demand for this flower actually be a new business opportunity? Noxious weed flower bouquets anyone?

Related Posts:

Party Time for Puncture Vine, Year Two

Party Time for Puncture Vine, Year Two

A noxious weed brought Boiseans together for the second year in a row. After a successful inaugural year, the Boise Goathead Fest returned to downtown Boise, Idaho on the 2nd and 3rd of August. The festival’s namesake comes from a particularly destructive weed whose spiky fruits are notorious for puncturing bike tires. Known commonly as goathead or puncture vine, Tribulus terrestris is abundant in the Treasure Valley and the bane of area bicyclists. Organized by the Boise Bicycle Project and other bike-centric non-profits, Boise Goathead Fest is a celebration of bike culture, as well as an opportunity to spread awareness about this problematic plant.

goathead-themed art

For the two months leading up to Goathead Fest, Treasure Valley residents were encouraged to pull as many goatheads as they could get their hands on. Those who took on the challenge were rewarded with tokens to be redeemed at the Fest for drinks or ice cream. Trophies and prizes were also presented to those who pulled the most goatheads over the two month period. This effort resulted in thousands of pounds of goatheads being removed from the area, saving bicyclists from countless flat tires and slimming down puncture vine’s extensive seed bank.

scale for weighing goathead collections

After two months of collecting goatheads, it was time to celebrate. The two day long party consisted of live music and DJs, a huge bike parade around downtown Boise (for which participants were encouraged to decorate their bikes and wear costumes), and a variety of other bike-themed and non bike-themed activities. Goathead education continued during the Fest with the help of folks from Ada County, City of Boise, Idaho Botanical Garden, and others.

A peak inside the Ada County Weed, Pest, and Mosquito Abatement education and outreach trailer

Goathead coloring page created by Wendy of Idaho Botanical Garden

Puncture vine pennants created by Anna of Idaho Botanical Garden

With all of this attention and awareness focused on a single noxious weed, might it be possible to eliminate it from our community and free ourselves from ruined rides and trashed tires? The seeds of puncture vine are relatively short lived, and as an annual plant, seeds are its only method of reproduction. Even if we can’t altogether eliminate it, we could certainly see a dramatic reduction in its abundance and distribution. Perhaps in the future we will spend less time pulling it and more time celebrating its rarity, reflecting back on the time when punctures permeated our pedal-powered lives. Whatever the result, puncture vine has brought our community together once again. If such a loathsome weed can bring people together in celebration like this, perhaps it’s not entirely bad.

me with goathead balloon

See Also: Boise Weekly – Goathead’s the Burr, Community’s the Word

Party Time for Puncture Vine at Boise Goathead Fest

When the Goathead Monster revealed itself before the big bike parade at the first annual Boise Goathead Fest, it was worried that the thousands of people it saw gathered before it were there out of hatred. After all, “rides have been ruined, tires have been trashed, and punctures have permeated” the “pedal-powered lives” of pretty much everyone in attendance, and the Goathead Monster was to blame. For that reason, hundreds (perhaps thousands) of pounds of puncture vine had been pulled around Boise throughout the month of July, all in preparation for this inaugural event.

Certainly, those of us who ride bikes regularly have a sore spot for this problematic plant. Yet, we weren’t there in anger. We were there to celebrate bicycles, community, friendship, and summer, and even if it took a villain like the Goathead Monster to bring us all together, how could we be mad?

My bike decorated with a papiermâchée goathead.

Bicycle events like this one have been a feature of summers in Boise, Idaho for years now. For over a decade, Tour de Fat was the main event, but after dropping Boise from its tour schedule starting this year, Boise (with New Belgium Brewing‘s continued support) was left to create its own thing. Boise Bicycle Project, along with the help of several other bike-centric and bike-friendly organizations, put together Boise Goathead Fest. The trappings are similar to Tour de Fat – a bike parade, along with music, food, drinks, costumes, games, and weirdness. The main difference is that this event is “bona fide Boise” … and goathead themed.

As a bicycle enthusiast, this is already my kind of event. As a plant nerd – and even more so, as a weeds-obsessed plant nerd – a noxious weed-themed festival is about as on the nose as you can get. Where else are you going to see people dressing up their bikes and themselves like a noxious weed? And where else are you going to find people who, despite their disdain for this plant (or perhaps because of it), decide to come together and celebrate? In a way, it makes me wish we could throw a party for all vilified plants, each one getting a chance to tell its story, and each one getting some time under the spotlight, in spite of the negative feelings we may have towards them.

Sierra rode in the parade dressed up as a Goat Buster.

Goathead is an easy plant to rally around. As executive director of Boise Bicycle Project said on Idaho Matters, goatheads are a “bane of bicycling, and they don’t discriminate. It doesn’t matter who you are, where you’re from, what sort of bicycle you’re riding … you’re going to get a flat tire from these things.” Perhaps other noxious weeds don’t quite have the charisma that puncture vine does – the ability to “unify everyone together” – but that’s okay. I’ll just have to find a way to celebrate each of them some other way. As it is, we now have Boise Goathead Fest, and if that means that every summer for years to come people will be donning goathead costumes and coming together to party in a positive way, what more can we ask for?

goathead art

more goathead art

The goathead monster is center stage.

bicycle-powered stage

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

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

Highlights from the Western Society of Weed Science Annual Meeting

Earlier this month, I went to Garden Grove, California to attend the 71st annual meeting of the Western Society of Weed Science. My trip was funded by an Education and Enrichment Award presented by the Pahove Chapter of the Idaho Native Plant Society. It was a great opportunity for a weeds-obsessed plant geek like myself to hang out with a bunch of weed scientists and learn about their latest research. What follows are a few highlights and takeaways from the meeting.

General Session

Apart from opening remarks and news/business-y stuff, the general session featured two invited speakers: soil ecologist Lydia Jennings and historian David Marley. Lydia’s talk was titled “Land Acknowledgement and Indigenous Knowledge in Science.” She started by sharing a website called Native Land, which features an image of the Earth overlayed with known “borders” of indigenous territories. By entering your address, you can see a list of the tribes that historically used the land you now inhabit. It is important for us to consider the history of the land we currently live and work on. Lydia then compared aspects of western science and indigenous science, pointing out ways they differ as well as ways they can be used in tandem. By collaborating with tribal nations, weed scientists can benefit from traditional ecological knowledge. Such knowledge, which has historically gone largely unrecognized in the scientific community, should receive more attention and acknowledgement.

David Marley was the comic relief. Well-versed in the history of Disneyland, he humorously presented a series of stories involving its creation. Little of what he had to say related to weed science, which he openly admitted along the way; however, one weeds related story stood out. Due to a lack of funds, the early years of Tomorrowland featured few landscape plants. To make up for that, Walt Disney had signs with fake Latin names created for some of the weeds.

Weeds of Range and Natural Areas

I spent the last half of the first day in the “Weeds of Range and Natural Areas” session where I learned about herbicide ballistic technology (i.e. killing plants from a helicopter with a paintball gun loaded with herbicide). This is one of the ways that Miconia calvescens invasions in Hawaii are being addressed. I also learned about research involving plant debris left over after logging. When heavy amounts of debris are left in place, scotch broom (Cytisus scoparius) infestations are thwarted. There was also a talk about controlling escaped garden loosestrife (Lysimachia punctata) populations in the Seattle area, as well as a few talks about efforts to control annual grasses like cheatgrass (Bromus tectorum) in sagebrush steppes. Clearly there are lots of weed issues in natural areas, as that only covers about half the talks.

Basic Biology and Ecology

On the morning of the second day, the “Basic Biology and Ecology” session held a discussion about weeds and climate change. As climate changes, weeds will adapt and find new locations to invade. Perhaps some weeds won’t be as problematic in certain areas, but other species are sure to take their place. Understanding the changes that are afoot and the ways that weeds will respond to them is paramount to successful weed management. This means documenting the traits of every weed species, including variations between and among populations of each species, so that predictions can be made about their behavior. It also means anticipating new weed species and determining ways in which weeds might exploit new conditions.

No doubt there is much to learn in order to adequately manage weeds in a changing climate. An idea brought up during the discussion that I was particularly intrigued by was using citizen scientists to help gather data about weeds. Similar to other organizations that collect phenological data from the public on a variety of species, a website could be set up for citizen scientists to report information about weeds in their area, perhaps something like this project in New Zealand. Of course, there are already a series of apps available in North America for citizen scientists to report invasive species sightings, so it seems this is already happening to some degree.

Teaching and Technology Transfer

A highlight of the afternoon’s “Teaching and Technology Transfer” session was learning about the Wyoming Restoration Challenge hosted by University of Wyoming Extension. This was a three year long contest in which thirteen teams were given a quarter-acre plot dominated by cheatgrass with the challenge to restore the plant community to a more productive and diverse state. Each team developed and carried out their own strategy and in the end were judged on a series of criteria including cheatgrass and other weed control, plant diversity, forage production, education and outreach, and scalability. Preliminary results can be seen here; read more about the challenge here and here.

And so much more…

Because multiple sessions were held simultaneously, I was unable to attend every talk. I also had to leave early on the third day, so I missed those talks as well. However, I did get a chance to sit in on a discussion about an increasingly troubling topic, herbicide-resistant weeds, which included a summary of regional listening sessions that have been taking place in order to bring more attention to the subject and establish a dialog with those most affected by it.

One final highlight was getting to meet up with Heather Olsen and talk to her briefly about her work in updating the Noxious Weed Field Guide for Utah. This work was aided by the Invasive Plant Inventory and Early Detection Prioritization Tool, which is something I hope to explore further.

If you are at all interested in weeds of the western states, the Western Society of Weed Science is a group you should meet. They are fun and friendly people who really know their weeds.

See Also: Highlights from the Alaska Invasive Species Workshop 

Summer of Weeds: Common Mullein

The fuzzy, gray-green leaves of common mullein are familiar and friendly enough that it can be hard to think of this plant as a weed. Verbascum thapsus is a member of the figwort family and is known by dozens of common names, including great mullein, Aaron’s rod, candlewick, velvet dock, blanket leaf, feltwort, and flannel plant. Its woolly leaves are warm and inviting and have a history of being used as added padding and insulation, tucked inside of clothing and shoes. In Wild Edible and Useful Plants of Idaho, Ray Vizgirdas writes, “the dried stalks are ideal for use as hand-drills to start fires; the flowers and leaves produce yellow dye; as a toilet paper substitute, the large fresh leaves are choice.”

Common mullein is a biennial that was introduced to eastern North America from Eurasia in the 1700’s as a medicinal plant and fish poison. By the late 1800’s it had reached the other side of the continent. In its first year it forms a rosette of woolly, oblong and/or lance-shaped leaves. After overwintering it produces a single flower stalk up to 6 feet tall. The woolly leaves continue along the flower stalk, gradually getting smaller in size until they reach the inflorescence, which is a long, dense, cylindrical spike. Sometimes the stalk branches out to form multiple inflorescences.

First year seedlings of common mullein (Verbascum thapsus)

The inflorescence doesn’t flower all at once; instead, a handful of flowers open at a time starting at the bottom of the spike and moving up in an irregular pattern. The process takes several weeks to complete. The flowers are about an inch wide and sulfur yellow with five petals. They have both female and male sex parts but are protogynous, meaning the female organs mature before the male organs. This encourages cross-pollination by insects. However, if pollination isn’t successful by the end of the day, the flowers self-pollinate as the petals close. Each flower produces a capsule full of a few hundred seeds, and each plant can produce up to 180,000 seeds. The seeds can remain viable for over 100 years, sitting in the soil waiting for just the right moment to sprout.

Common mullein is a friend of bare, recently disturbed soil. It is rare to see this plant growing in thickly vegetated areas. As an early successional plant, its populations can be abundant immediately after a disturbance, but they do not persist once other plants have filled in the gaps. Instead they wait in seed form for the next disturbance that will give them the opportunity to rise again. They can be a pest in gardens and farm fields due to regular soil disturbance, and are often abundant in pastures and rangelands because livestock avoid eating their hairy leaves. Because of its ephemeral nature, it is generally not considered a major weed; however, it is on Colorado’s noxious weed list.

Several features make common mullein a great example of a drought-adapted plant. Its fleshy, branching taproot can reach deep into the soil to find moisture, the thick hairs on the leaves help reduce water loss via transpiration, and the way the leaves are arranged and angled on the stalk can help direct rain water down toward the roots.

Common mullein has an extensive history of ethnobotanical uses. Medicinally it has been used internally to treat coughs, colds, asthma, bronchitis, and kidney infections; and as a poultice to treat warts, slivers, and swelling. The dried flower stalks have been used to make torches, and the fuzzy leaves have been used as tinder for fire-making and wicks in lamps.

The hairy leafscape of common mullein (Verbascum thapsus)

More Resources:

Quote of the Week:

From Gaia’s Garden by Toby Hemenway

Here’s why opportunistic plants are so successful. When we clear land or carve a forest into fragments, we’re creating lots of open niches. All that sunny space and bare soil is just crying out to be colongized by light- and fertlity-absorbing green matter. Nature will quickly conjure up as much biomass as possible to capture the bounty, by seeding low-growing ‘weeds’ into a clearing or, better yet, sprouting a tall thicket stretching into all three dimensions to more effectively absorb light and develop deep roots. … When humans make a clearing, nature leaps in, working furiously to rebuild an intact humus and fungal layer, harvest energy, and reconstruct all the cycles and connections that have been severed. A thicket of fast-growing pioneer plants, packing a lot of biomass into a small space, is a very effective way to do this. … And [nature] doesn’t care if a nitrogen fixer or a soil-stabilizing plant arrived via continental drift or a bulldozer’s treads, as long as it can quickly stitch a functioning ecosystem together.