Many plants sharing our gardens are not natives but imports from other lands. At the time, introducing the species probably seemed like a good idea, that is until it turns invasive and deadly.

Scotch broom (Courtesy of King County)

Scotch Broom is a perennial shrub with lovely yellow pea-like flowers, dark green stems, and evil on its mind. OK I made up the evil part, but the more you know about Scotch Broom the more you might agree.

History

Scotch Broom was introduced in the US in the early 1800s.

History indicates that broom was imported as domestic sheep fodder. But, broom may have been imported for its wide variety of medical and utility functions.

Medical ailments treated included (Note: This weed is poisonous. Modern medicines provide safer alternatives):   

Heart problemsHemophiliaRheumatismGout
JaundiceKidney stonesRespiratory conditionsSnake Bite
Sore musclesInfectionsPurgativeEmetic

Utility functions included hair rinse, leather tanning, sweeping brooms, thatched roofs, rope, beer flavoring, yellow dye, and a substitute for hops, capers, and coffee. In addition, Scotch Broom roots host nitrogen-fixing bacteria which help the plant colonize nutrient-poor soils.

It is native to much of Europe and Africa where natural predators for the plant evolved.

In the early 1900’s, broom was planted to prevent soil erosion along Pacific Coast highways. It probably seemed like a great idea at the time.

It didn’t take very long for Scotch broom to become an international superstar pest. Today, broom is considered a pest throughout most of its range.

More than just one

Does it seem like the Scotch broom blooms more than once a year? Well, it does, kinda. There is more than one type of broom and more than one type lives on the Oregon Coast.  

The ranges for Scotch, Spanish, French, and Portuguese broom overlap. You may notice different bloom seasons, lighter color flowers, height differences, and more.  All have a nice yellowish bloom similar to a pea.

Scotch broom and Gorse are sometimes confused (Gorse is very stickery). They both grows in similar conditions, and cause similar problems, but are different species.  

Pest Status

This plant has earned its weed status well by aggressively invading many areas. Once in place it is very difficult to get rid of and control. What makes it so bad?

Broom regenerates quickly, forming dense stands. These stands are unpalatable and somewhat poisonous to wildlife. They will become so dense that even quail cannot live there.  

These thick dense stands will also prevent normal reforestation and regeneration processes and drive many native species out by shading, increasing soil acidity, and toxicity.  

Broom increases fire hazard frequency and intensity. It is one of the most flammable plants there is and poses enormous threat to communities.

It creates a high fire hazard frequency and intensity. Even green, the shrubs will cause a fire to erupt. The broom is one of the most flammable plants there is and poses an enormous threat to our community’s fire safety. 

Seeds

The plant is a prolific seeder and can release 20,000 or more seeds per plant every year. Seeds stock pile over time until destroyed or germinated. Seed remain viable in the soil for decades and any disturbance can cause the seed to germinate.

Seeds will germinate after a ‘cooler’ fire (depending on the temperature of the fire). Hot fires can destroy the seeds.

It is hard to get rid of….

The only way to control this plant is through repetitive and ongoing treatments. Treatments include manual removal, chemicals, burning (hot), shading through planting, and some biological options (Bruhidius villosus, exapion fascirostre, and Leucoptera spartifoliella).

Once established, the plant is very drought tolerant. This tolerance makes herbicides less effective during certain times of the year.

So Expensive

Scotch Broom causes substantial timber revenue losses and costs a lot to control – somewhere over $40 million a year in Oregon alone.

REFERENCES:
–OSU Extension Service (https://extension.oregonstate.edu/news/scotch-broom-beautiful-noxious)
–WebMD (https://www.webmd.com/vitamins/ai/ingredientmono-375/scotch-broom)
–King County, Scotch Broom (https://bit.ly/2X7XvAh)
–Scotch Broom (https://www.invasivespeciesinfo.gov/profile/scotch-broom)
–The News Review, Ask a Master Gardener… (https://bit.ly/2X9v4Sq)
–USDA Fire Effects Information System (FEIS) (https://bit.ly/3gar3ol)
–Wikipedia, Cytisus scoparius (https://en.wikipedia.org/wiki/Cytisus_scoparius)
–Weeds, Working Lands (https://bit.ly/30TRtUO)

Walk along the beach. All kinds of things wash ashore, including kelp.

Bullwhip Kelp washed ashore

There is a good chance you can find a fresh piece of dark olive-brown Bullwhip Kelp. Storms and strong waves will occasionally tear pieces of the plant and throw them onshore. Sometimes the rough water can destroy a whole kelp forest.  

The idea of a kelp forest might be new to you. They are very similar to land, or terrestrial, forests…just wetter. A kelp forest has a canopy which supports sun-loving organisms and leaves. It also has a partially-shady middle section (with a very strong stalk) and darkly-shaded seafloor which acts as a nursery for new plants.

Where Found

Bullwhip kelp grows on rocks found in low to subtidal zones at depths up to 100 feet. It prefers semi-exposed habits and high-current areas. Offshore beds in deeper water may persist for several years.

Bullwhip kelp is found along the North American Pacific Coast from Alaska south to northwest Baja California, Mexico.

Plant Parts

Like land plants, kelp has leaves or ‘blades’ that can reach up to 13 feet long and nearly six inches wide. These leaves form the canopy cover and are often produced annually. Blades hang on for up to 18 months (depending on the weather and other conditions).

Numerous blades (30-64) sprout from a floating bladder. This bladder contains carbon monoxide which helps keep the blades in the sunny canopy.

Bladders connect to a long hollow flexible stalk, or stipe, which resembles an enlarged whip (i.e., the name sake). The stalk is very strong and has a fist-sized holdfast (think root-like structure) that grips onto the rocks.

Ecosystem support

Kelp forests offer protection and food for a variety of species besides human. This includes urchins, fish, invertebrates such as shrimp, snails (like Black turban snails), and brittle stars and worms. Marine mammals include whales, otters, seals, and sea lions, and shore bird such as great blue herons, snowy egrets, and cormorants also depend on kelp.   

Gives a whole new meaning to ‘kelp bed’ eh?

Reproduction

Kelp can form large forests or small beds. Different species of kelp often grow together favoring different depths and exposure.  

Bullwhip kelp drops mature spore patches to the seafloor near the parent’s holdfast which creates dense forests. It is the only kelp to do that.

Uses

Bullwhip kelp is edible and can be enjoyed dried, raw and/or picked. For a pickle recipe see Monterey Bay Seaweed (http://www.montereybayseaweeds.com/the-seaweed-source/tag/bullwhip+kelp).

Pacific Northwest Coastal Tribes used the kelp for creating a number of different products such as fishing lines and nets, ropes, and lightweight storage containers. It was also used for steaming and shaping various woods to create halibut fishing hooks and Yew bows.

Fresh kelp could also be eaten or included in recipes for cakes, curry, and chutney. It has also been used for pharmaceutical supplies, poultry feed, dairy products, and finishing agents.

But wait there’s more…

There are theories that kelp forests may have helped colonize the Americas. I can hear the disbelief in your laughing from here…  

Suppose that huge kelp forests stretched from northeast Asia to the northern American Pacific coasts.

These forests could have provided food and game, and buffered rough water and potentially acted as a highway for ancient colonists (and not just humans).  

Next time you see this lowly plant washed ashore and shredded from a storm, consider… “Did this plant make it possible for you to wiggle your toes in the sand today?”

Perhaps without it, explorers may not have survived the treacherous trip here. Certainly, food for thought!

REFERENCES:
–Wikipedia, Nereocytis (https://en.wikipedia.org/wiki/Nereocystis) and Kelp forests (…kelp_forests)
–Island Herbs (http://ryandrum.com/articlekelp.html)
–Bull Whip Kelp (https://bit.ly/2CINwuf)

And I’d like to give my love to everybody, and
let them know that the grass may look greener on the other side,
but believe me, it’s just as hard to cut.

Little Richard
Beachgrass in the sunset, royalty free, Unsplash

As environmental mis-steps go, planting European Beachgrass at Golden Gate Park, San Francisco, in the late 1800s probably seemed like a great idea. This grass successfully stabilized dunes in Europe and North Africa and many agencies planted thousands of acres, much of it in Oregon.

It seemed like such a good idea

European Beachgrass forms stiff, hardy clumps of grass that can reach nearly four feet tall. A strong rhizome mat holds clumps erect and facilitate fast colonization across an area. One small clump can produce 100 new shoots annually.

This plant provided a faster way to stabilize sand dunes, had few pests and predators, and grows very densely. The grass changes the shape of a dune and overall native ecology by displacing plants and animals by creating higher, steeper curve on the ocean side of a dune. This decreases sand flow to interior dunes impacting the long-term development of the whole coastal ecosystem.

Beachgrass on dune, royalty free Unsplash

One tough grass

Not only does European Beachgrass grow fast and dense, but it will tolerate a number of adverse conditions. For instance, the plant will survive for extended periods of time when buried by sea water and/or sand. In such a disturbance, rhizome pieces will break off. These pieces begin growing in new sites.

It will also grow in a variety of conditions both in pH, mineral or chemical issues, temperatures, and as a perennial live many years. A fungus that grows on the grass, may also make dunes less fertile and thus less likely to support other plants.

The impact?

Beachgrass is one of the most pervasive exotic plant species threatening the West Coast. It is everywhere and not only creating problems for plants but animals such as the endangered western snowy plover by increasing predator cover.

This noxious weed grows from California north along the Pacific coast into British Columbia. This grass was also planted in New Zealand and Western Australia and is considered noxious.

Is it controllable?

Maybe. Interest in controlling began about 1980. Finding a method that is effective, inexpensive, minimally invasive to other native species, flexible enough to use on steep slopes, and acceptable to a wide variety of land owner/managers is a tough challenge.   

Several research projects have been underway for years looking at various removal techniques such as manual, mechanical, chemical, and fire alternatives. Other methods are still being sought.

REFERENCES:
–US Dept. of Agriculture (https://plants.usda.gov/core/profile?symbol=AMAR4)
–California Invasive Plant Council (https://www.cal-ipc.org/plants/paf/ammophila-arenaria-plant-assessment-form/, https://www.cal-ipc.org/wp-content/uploads/2019/01/Cal_IPC_Symposium_2018_Monique_Silva-Crossman_Effects-_of_Ammophila_arenaria_removal.pdf, and https://www.cal-ipc.org/wp-content/uploads/2017/12/1997_symposium_proceedings1934.pdf)
–Wikipedia, Ammophila Arenaria (https://en.wikipedia.org/wiki/Ammophila_arenaria)
–AZ Quotes (https://www.azquotes.com/quotes/topics/greener-on-the-other-side.html)