Know your herbs: Slippery Elm, the most threatened herb of “least concern”

Slippery elm is listed on the United Plant Savers' “At-Risk”. This is largely due to overharvesting and incorrect harvesting, such as removing bark directly from the trunk rather than the branches.

Slippery elm (Ulmus rubra) is a tree native throughout a large tract of America from North Dakota to Texas and over to the Atlantic Ocean and parts of Canada. However, this seemingly large footprint belies its fragile existence in a wellness marketplace voracious for cheap supplements.  

Its Habitat: 

Slippery elm trees thrive where there is plentiful limestone-rich soil on the forest floor alongside rivers and creeks.  

Its Lifespan: 

Slippery elm trees are bicentenarians by nature. In a perfect world, undisturbed by climate change or the chainsaw, they would live for up to 200 years.  

Its Reproduction: 

Slippery elms are gracefully pollinated by the wind, which collects their circular winged seeds for dispersion throughout the surrounding forest.  

Its Threats:  

The tree faces significant threats that have led to its decline in many areas, and it is considered at-risk, scarce, or even legally protected in several states and provinces (in the US and Canada). 

The primary threats to slippery elm are: 

• Dutch Elm Disease (DED): This introduced fungal disease has been devastating to all native elm species. DED has killed millions of mature trees, severely reducing populations and preventing many new trees from reaching maturity. 

• Overharvesting for Herbal Use: This is the most direct threat related to Slippery Elm as a species. The medicinal part of the tree is the inner bark (cambium layer). 

• Destructive Harvesting: Harvesting the bark kills the tree. Unlike plants where you harvest leaves or fruits, stripping the bark girdles the tree, cutting off its nutrient and water flow. 

• Impact on Population: The combination of a disease-decimated population and targeted harvesting for the herbal trade has created a critical situation in many regions. 

This leads me to the conundrum this herb is facing, which is, how slippery elm is classified in plant politics and how that translates into consumerism... (at its peril!).  

The IUCN (International Union for Conservation of Nature) has classified Slippery Elm (Ulmus rubra) at a global level as "Least Concern". Meaning that across its entire native range (eastern North America), it is not currently at a high risk of extinction. 

However, it is considered “threatened" by conservationists and Governments at a local and regional level.  

• In the U.S.: It is listed as "endangered" in Florida and "exploitably vulnerable" in New York. 

• In Canada: It is a species of special concern. It is listed as "endangered" in Ontario and is protected under the Endangered Species. This makes its harvest and trade illegal. 

  
  

I would like to insert a point to note here, about the terminology ‘wild harvested’ versus ‘commercially cultivated’. This adds weight to the debate around whether a plant is potentially endangered or not.  

Wild Harvested (aka Wildcrafted, Gathered, Foraged) may sound organic, whimsical and like best practice, BUT it’s shorthand for ‘taken directly from nature’. 

• Technical Definition: The practice of collecting plants or plant parts (e.g., bark, roots, leaves, berries) from their natural, wild habitat—they are not planted, irrigated, or managed as a crop. 

  
  

Commercially Cultivated (aka Farmed) may unromantically sound large scale or industrial, BUT it means the plant is being grown and regrown specifically for a purpose, i.e. it’s sustainable.  

• Technical Definition: The intentional, agricultural practice of planting, tending, and harvesting plants in a controlled environment for commercial sale.  

  
  

These are the only two methods for obtaining herbs for the health and wellness industry. The former is more often than not... not ethical or sustainable. In the case of slippery elm, wild-harvested = species loss. Regardless of where it’s being wild-harvested in the world.

Don’t forget, these trees would normally live for around 200 years (without being killed for their bark) in very fragile ecosystems (along riverbanks and creeks) that are also facing environmental devastation.  

Therefore, Is It Ethical to use Cheap Wellness Supplements? 

It is very difficult to argue that the widespread use of slippery elm in cheap, mass-market supplements is ethical. Here's why: 

1. The Source is Almost Certainly Unsustainable: A "cheap wellness supplement" implies a high volume, low-cost product. Given that sustainable, cultivated sources are rare and wild populations are stressed, this low price point almost certainly relies on wild harvesting that is not managed for long-term survival. The low cost externalises the true environmental cost of depleting a native species. 

2. Cultivation is Not the Norm: Slippery Elm is not widely cultivated on a commercial scale like Echinacea or Goldenseal (both of which have sustainability issues). It is a slow-growing tree, and farming it for bark is not economically viable for a "cheap" product. Therefore, the vast majority of bark in the supply chain is wild-harvested. 

3. The Harvest is Lethal: As stated, harvesting the bark kills the tree. Ethical wildcrafting guidelines are based on taking a small percentage of a population without harming it (e.g., leaves, seeds, or a branch). This is not possible with Slippery Elm bark harvest. 

4. It's a Keystone Species: Elm trees are important for their ecosystems. They provide food for wildlife and are a host for butterfly larvae. Removing them has a ripple effect on the forest's health. 

   
   

If you feel the herb is necessary for your wellness, it is your responsibility to seek out a supplier that can transparently verify (with a certification like United Plant Savers or FairWild) that their product comes from a cultivated or verifiably certified sustainable wild-harvested source.  

Be prepared to pay a premium, as ethical sourcing costs more. For most people, considering alternative herbs with better sustainability profiles is the most responsible choice.  

Great alternatives to slippery elm are: Marshmallow (Althaea officinalis), Comfrey (Symphytum spp.), and Mullein (Verbascum spp.) have been suggested by herbalists as potential alternatives for slippery elm bark. Please consult your doctor before taking Ulmus rubra or any other medicinal plant. 

Key Points to Remember: 

• Slippery Elm is not widely cultivated on a commercial scale 

• It is a slow-growing tree that can (normally) live for up to 200 years 

• Dutch Elm Disease has killed millions of mature trees 

• The medicinal part of the tree is the inner bark 

• Harvesting the bark kills the tree 

• Elm trees are a ‘keystone’ species that other plants and animals depend upon for their survival  

• Their absence has a ripple effect on the forest's health  

Slippery Elm trees can live up to 200 years, though their susceptibility to diseases such as Dutch Elm and harvesting for their bark means that their actual lifespans are usually much shorter.

The Facts on Dutch Elm Disease (DED) 

Dutch Elm Disease (DED) is not endemic to the United States. It is an invasive, non-native pathogen that was introduced to the U.S. from elsewhere. 

The disease was first identified and described by Dutch scientists in the 1920s (hence the name "Dutch" Elm Disease), but the pathogen itself is believed to have originated in Asia. 

DED was accidentally introduced to North America in the early 20th century. 

• The first major outbreak in the U.S. began around 1930. 

• It is thought to have arrived on a shipment of infected elm logs from Europe, which were intended for veneer manufacturing. 

North American elm species, like the American Elm (Ulmus americana) and Slippery Elm (Ulmus rubra), had no evolutionary history with this fungus and therefore had little to no natural resistance. This made them extremely susceptible, leading to catastrophic die-offs.