Bull Thistle - A Real Weed

Most people regard all thistles as invasive weeds. I happen to think they are beautiful and I have taken photos of them all over the world.

Recently we had a thistle sprout in the driveway. I decided to let it grow. Several species of thistle are native to Southern California and their nodding flower heads provide seed for our local lesser goldfinches and house finches. The down that creates the parachute to help spread the seed is used by a variety of birds and small creatures to provide plush comfort to their nests and homes.

The thistle in the drive has flowered and I think it is lovely–prickly, but delicate.

However, after consulting a few books and two reliable websites Oregon State University and Invasive.org, I have identified my thistle as a bull thistle (Cirsium vulgare) a European / western Asian import. The “vulgare” in its scientific name means common. This imported thistle can be highly invasive and problematic.

For the sake of my local wild environment, this thistle must go.

Some “weeds” are welcome additions to your backyard biodiversity, others are not. If you have a thistle find out if it is a beneficial native or a problematic invasive and act from a position of knowledge.

Letting Go of the Word “Weed”

The dictionary defines a weed as “a wild plant growing where it is not wanted and in competition with cultivated plants.”

I’m letting go of this notion that wild free-growing plants are unwanted. And in doing so, amazing things are growing in my yard.

This wild cucumber or manroot (Mara macrocarpus) creates a beautiful delicate vine with white flowers in early spring. Now the fruit, these amazing prickly orbs the size of baseballs, are maturing and creating an exotic look. Because this vine is a native, it won’t grow out of control. It will die back to just its root during the summer.

But I didn’t plant this beautiful vine; it appeared.

The easiest way to increase native plants in your yard is to embrace the wild plants that show up on their own.

In an attempt to “control” nature, we label things as “weeds” and yank out the hearty native foliage that sprouts in our yards. Yet these plants typically are best suited for our soil, climate and water availability. These plants often are transported by native animals that depend on this vegetation for food and thereby spread the plant’s seeds.

Some plants that appear can be very invasive, but usually these are not native species. In my own yard I have a terrible problem with Oxalis pes-caprae, a South African species. Nothing eats it, it spreads uncontrollably and it pushes out other plants.

Native species usually have some creature or climate adaptation that controls their growth or spread. Before you pull out a new plant in your yard, identify it. Know What You Grow.

Earlier this year I discovered a black nightshade that had been introduced to the yard. At first I didn’t know what it was. But a friend saw my photos and identified the plant. A little research revealed that the black nightshade is an important native food source for some animals. I left it in. It is growing beautifully with purplish fruit, but the two plants have stayed small and have not spread.

I also have stopped trying to control my natives. I let a young mallow take hold about a yard from its original planted parent. Wild plants grow in the spots that are best suited for them. Yes, if a plant sprouts in a pathway I will remove it, but these self-starters are more likely to thrive in the locations they have chosen.

The valley scrub oak (Quercus agrifolia), that we lovingly planted 12 years ago, died in last year’s drought. But the four valley scrub oaks that were naturally planted by scrub jays are all healthy and growing. Toyon, Catalina cherry and holly cherry, are all natives reproducing naturally and becoming vital to erosion control on our hillside.

It’s my intention to create habitat in my yard, so I am letting go of the word “weed.” I’m embracing the wild plants that find their way to grow in our corner of the city and increase our backyard biodiversity.