Friendly vs. Invasive Plants: What is the difference?

a guest post from the Sea to Sky Invasive Species Council

You’ve likely heard someone describe a plant as a weed, native, non-native or invasive. But you may have struggled to determine which of these plants are friendly or otherwise. Well, the Sea to Sky Invasive Species Council is here to help!

  • Weed: A plant growing where it is unwanted, likely as it is competing with cultivated plants. 
  • Native (indigenous): A plant that occurs naturally in a given ecosystem. 
  • Non-Native (introduced, exotic): A plant that was introduced to a given ecosystem.
  • Invasive: A plant that was introduced to a given ecosystem and is likely to cause environmental, economic, or human health concerns.  

Without doing some research, it can be tricky to ascertain a plant’s classification.

One tell-tale sign of a native species is whether that plant fits harmoniously within the food web. Native plants have evolved with and against their “allies” and “enemies” for thousands of years. Consequently, a native plant may have a specially-adapted pollinator or predator and may have built resistance to certain pests or diseases too. They play a crucial role in local ecosystems by providing habitat, food, and other benefits to biodiversity.

In contrast, invasive plants have not evolved in our local ecosystems and thus lack ecological checks and balances. This leads to their rapid, nearly uncontrollable spread, which disrupts the natural processes that occur in nature. 

Non-native plants share qualities of both: they generally do not have specialized relationships with other species, but they also do not dominate a landscape.

Sometimes, however, the differences get blurred. Indeed, a weed is a subjective term and plants can be weedy and either native, non-native, or invasive. For instance, the native Fireweed is commonly considered a weed when it shows up uninvited in gardens.

Moreover, classifications are both space and time scale-dependent. In particular, climate change (past and present) has dramatically altered the conditions of ecosystems, pushing species outside their native range. Thus, a species that once was native to an ecosystem may no longer amicably inhabit a region. 

All of this is to say it is important to know your enemy.

  • Invasive Ivy tends to crawl up trees, which can kill the tree by blocking sunlight and essential nutrients.
  • Start by familiarizing yourself with invasive plants in the Sea to Sky region. This is especially important if you are an avid gardener or plant collector, as you are likely to encounter invasive species at the garden store.

    Resist the urge to buy invasive plants and use the Grow Me Instead guide for native and exotic plant alternatives. Not only can native and introduced plants provide direct replacements for harmful invasives, but studies have shown that increased native biodiversity confers resistance to invasion.

    So, if native plants are looking out for us, let’s look out for them too!

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