Flat-Top Broomrape: A Parasitic Wildflower You Won’t Want in Your Garden
Meet the flat-top broomrape (Orobanche corymbosa), a fascinating yet problematic native plant that’s more of a botanical curiosity than a garden companion. This unusual annual belongs to a group of plants that have given up the traditional way of life—photosynthesis—in favor of a more parasitic lifestyle.
What Makes Flat-Top Broomrape Special (and Concerning)
Flat-top broomrape is a native forb found across western North America, from British Columbia down through the western United States including California, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming. As a true native species, it plays a role in natural ecosystems, but that doesn’t mean you’ll want to welcome it into your garden.
This plant is what botanists call a holoparasite—it’s completely dependent on other plants for survival. Unlike most plants that make their own food through photosynthesis, flat-top broomrape latches onto the roots of host plants and steals nutrients directly from them.
Identifying Flat-Top Broomrape
You’ll recognize flat-top broomrape by its distinctive appearance:
- Clusters of small, yellowish to purplish flowers arranged in flat-topped groups (hence the name)
- Thick, fleshy stems that emerge from the ground
- Scale-like structures instead of true leaves
- No green coloration, since it doesn’t photosynthesize
- Height typically ranges from a few inches to about a foot tall
Why You Shouldn’t Plant Flat-Top Broomrape
While this plant is a legitimate native species, it’s definitely not garden material. Here’s why:
- It’s parasitic and will weaken or potentially kill your garden plants
- It particularly targets plants in the sunflower family, including beloved garden artemisia species
- You can’t actually cultivate it in the traditional sense—it requires living host plants to survive
- Once established, it can be difficult to eliminate
What to Do If You Find It
If flat-top broomrape shows up in your garden naturally (which can happen since it’s native to much of western North America), you’ll want to remove it promptly to protect your other plants. The best approach is to carefully dig up the entire plant, including the underground portions that connect to host plant roots.
Since this is an annual plant, preventing seed production is key to long-term control. Remove any flowers before they can set seed, and monitor the area for new growth in subsequent growing seasons.
Native Alternatives for Your Garden
Instead of this parasitic native, consider these beautiful and beneficial western native plants:
- Native penstemons for colorful flower spikes
- Wild bergamot for pollinator-friendly blooms
- Native lupines for stunning flower displays
- Blanket flower for long-lasting color
The Bottom Line
Flat-top broomrape is a perfect example of how not all native plants are suitable for gardens. While it has its place in natural ecosystems, this parasitic annual can cause real problems for gardeners. If you encounter it, appreciate it for the botanical oddity it is, but don’t let it stick around to harm your cherished garden plants. There are plenty of other gorgeous native options that will enhance your landscape without playing the role of botanical vampire.
