Editor’s note: This is the second in a series of five articles during April, Native Plant Appreciation Month, about the importance of native plant landscaping in the Snohomish County garden.
Many people view native plants as something they can have, like granola. They are vital to our environment’s health.
To understand why, we need to start with insects. As mentioned in last week’s article, they are the central players holding together the environmental web. Our birds are a good example. Although songbirds eat seeds, berries, and bird feeders for their food, insects are essential for their survival and for feeding their young. Caterpillars are a particularly important source of food.
What does this mean for native plants? Around 90% of plant-eating insects consider themselves specialists. This means that they depend on a single or a few plant species to survive. This is illustrated by the monarch butterfly, which, during its caterpillar stage depends on milkweed plants for food. 96% of monarch butterflies have been lost since the eradication of milkweed.
Why do insects specialize so much? It all comes down to the fact that plants don’t like to be eaten. They use a variety of toxins and other defenses to protect themselves. Over thousands of years, insects and other plant-eaters have developed ways to overcome these defenses. The sticky white sap that is excreted from milkweed’s leaves gives it its name. The sap can clog the mouths of potential insect predators. Monarch caterpillars have found a way around this problem by removing the main vein from the leaf and allowing the sap to drain away before they eat the rest of it. Many insects can be stopped by milkweed’s potent toxins. Monarchs have discovered enzymes that reduce the toxic effects of those toxins. They’ve even learned to hijack the milkweeds defenses by storing the toxins in their wings, which helps ward off their predators.
While monarchs and milkweed may not be native to the Northwest region, there are many interdependent relationships among species that are native.
This time of year, native Anna’s hummingbirds thrive on the nectar of the native flowering currant. (William McClain)
Native plants have an unfair advantage over non-native plants. They lack the insects and predators that they have evolved to overcome over thousands of generations. They replace native plants in open spaces, highway margins, and conservation areas without natural predators. This results in a drop in insect populations, especially caterpillars. Our songbirds are then extinct. The decline in bird population ripples through the food web, affecting raptors as well as other predators at higher levels. English ivy and English holly are examples of non-native aggressive plants found in our region.
We are only beginning to understand the ways native plants interact with each others. British Columbia was the first to discover this when it came to investigating why Douglas Firs became ill after their birch tree neighbors were removed. It was found that the trees were exchanging nutrients through soil fungus connections between their root systems. This arrangement was advantageous to both tree species. These connections are not available to non-native plants because they take many thousands years to develop.
It is clear that native plants are beneficial to the environment in many ways. That’s not to say that everyone should be expected to completely rip out an existing landscape in order to replace it with natives. Natives should be considered whenever you add or replace plants or if you want to improve your existing landscaping.
The native flowering currant is adaptable to a variety conditions and can provide vibrant spring color. (Herald photo)
When selecting plant species, consider the site conditions. These include how much sunlight you have, soil moisture and condition, slope, drainage, space, and space. You will be able take advantage of all the expert resources to help you select plants. It’s important to identify plant species that will thrive in the conditions your site offers. Our native flowering currant, a favorite, can tolerate a wide range of conditions. It’s prized for its early spring color, and appreciated by our native Anna’s hummingbirds as a source of nectar at a time of year when other options are less plentiful.
Explore these websites
For more information about native plants, visit Washington Native Plant Society website. www.wnps.org. You can also link to our local Salal Chapter on their website. www.wnps.org/salal.
The National Audubon Society also has information about bird-friendly gardens and a directory of native-plants which might be useful to you (www.audubon.org/PLANTSFORBIRDS). Also, their “Plant for Birds” sign can help start conversations with neighbors about wildlife-friendly gardens (tinyurl.com/EDH-audubon).
If you’d like to view native plantings first-hand, consider visiting the Edmonds Wildlife Habitat & Native Plant Demonstration Garden sponsored by Pilchuck Audubon Society, our local Chapter of the National Audubon Society (www.pilchuckaudubon.org/edmonds-wildlife-habitat-native-plant-demonstration-garden). It’s located at 95 Pine St. in Edmonds. You can also visit Salal Native Plant Garden. This is a collaboration between Salal Chapter and Washington State University Agriculture Extension. It’s located at 16650 State Route 536 in Mount Vernon (www.wnps.org/salal-programs/garden).
Snohomish County Public Works maintains an inventory of nurseries in Snohomish and King counties that sell native plants. tinyurl.com/EDH-nurseries.
Next week’s article will explore how your garden’s soil plays a key role in your landscape’s environmental productivity. We’ll discuss the numerous benefits of taking a natural approach to maintaining soil health.
William McClain, a Lynnwood resident, is a member the Pilchuck Audobon Society. A native Washingtonian, he published his first novel, “The Risk in Crossing Borders,” in 2020 after retiring from a career in benefits consulting. He plans to publish a second novel in 2023 set in England during World War II. He enjoys hiking, nature photography, and playing football.
