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Putting Invasive Plants to Use: Medicinal Invasives of Sonoma County


My name is Sophia and I am a fellow at Pepperwood Preserve in Santa Rosa. I have lived in Sonoma County for 5 years, moving here for college and because I wanted to be near more open space and accessible nature, specifically close to the forests and wildflowers. While living here I have developed some new hobbies, one of which i’ll be writing about today; ethical foraging!

Ethnobotany is “the scientific study of the traditional knowledge and customs of a people concerning plants and their medical, religious, and other uses” (Oxford). I connect most to a landscape when I learn about the ethnobotanical uses of the native plants. I struggle to remember latin names or learn plant taxonomy, but when I connect a plant to a story or use by humans I can recall it much easier. Sonoma County is full of medicinal native plants such as Mugwort (Artemisia douglasiana), Elderberry (Sambucus nigra), and Sticky Monkey Flower (Mimulus aurantiacus) that have been used by the original stewards of this land such as the Wappo, Pomo and Miwok tribes. I do occasionally harvest medicinal native plants however what this blog will focus on is medicinal non native plants. There are plenty of non native and invasives with medicinal uses such as Cleavers (Galium aparine), Mullein (Verbascum thapsus), and a personal favorite, St John’s Wort (Hypericum perforatum) in Sonoma County, and harvesting them can be a way of reducing their spread.

If you are going to forage for native plants please keep in mind that you are a guest and also a steward with a responsibility to leave enough for others, enough for regeneration, and enough for the other animals to eat. You should never take more than 50% of a plant, preferably leaving up to 66%. If a plant is endangered or culturally significant such as white sage, don’t touch it. Have some self control. Additionally, HARVEST INVASIVES AND NON NATIVES FIRST! You don’t need to leave any for the next person if it's invasive, take the whole plant!

Ok, now that we’ve got the housekeeping of foraging covered, here's the fun part: how to use medicinal non native plants!


St. John’s Wort - identified by its yellow flowers that bleed red when crushed and when its leaves are held up to the sun, you can see tiny dots poked into them. Generally pops up in Northern California in the late spring then blooms in the summer. Now (June) is a great time for harvesting. Pick the flowers and leave them out on a dry surface to let any bugs crawl out, then transfer to a brown paper bag in a cool dry place and shake every couple days to let it fully dry. Once dry, the flowers can be used as a tea or put into a salve for topical use.

For internal use: St John’s Wort is a powerful herb used to treat depression, anxiety, ADHD and menopausal symptoms and is clinically prescribed in parts of Europe. This herb should NOT be taken in addition to antidepressants and you should always check if your medication is compatible with herbs you are foraging for internal use. For more information click here

For topical: St John’s Wort is great for healing skin sores, inflammation, bruising and muscle pain. I make salves using SJW distilled into olive oil for about 6 weeks then mixed into shea butter and beeswax. SJW will make your skin more sensitive to sunlight so always wear sunscreen after using it topically.

Mullein - Popping up from spring to fall, harvest the big fuzzy leaves, dry out entirely and then use in a tea for lung agitation and respiratory issues. Steep mullein tea through a coffee filter as the fuzzy hairs can themselves be an irritant. I highly recommend a mullein and oregano tea blend during fire season to help with smoke irritation.

Cleavers - found in the spring and summer, sometimes called velcro plant. Harvest the entire above ground portion and use in a tea as a diuretic to aid in urinary and kidney issues and inflammation. Very hydrating and great when mixed with honey!

Happy harvesting! - Sophia :)

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