Late season bloomer: Common tarweed (Madia elegans)

Long before valley-bottom fields, grasslands and open areas in the Klamath-Siskiyou bioregion were covered in non-native and invasive star thistle (Centaurea solstitialis) or dyer’s woad (Isatis tinctoria), some were covered with the dainty, yellow, daisy-like flowers of the native common tarweed (Madia elegans). Tarweed is an annual wildflower in the sunflower family. In the Klamath-Siskiyou it occurs in grasslands and open forest, typically at mid to low elevation. It flowers in summer and early autumn, from northern Oregon through the California Floristic Province and Great Basin Province south to Baja California. The flowers curl up during the daytime, opening late in the day and remaining open until the middle of the next morning. (An explanation of why can be read in this SF Gate article.) The foliage exudes fragrant oil, and the plants are sticky, hence the common name tarweed. It is an often-overlooked native plant that deserves more respect and attention. The seeds of tarweed are eaten by many birds and small mammals, such as mourning doves, quail, blackbirds, finches, Oregon juncos, California horned larks, western meadowlarks, American pipits, sparrows, towhees, mice, ground squirrels and chipmunks. Being a late bloomer, tarweed is an important late nectar source for butterflies, bees and other beneficial insects.

Once, while picking tarweed seed, I discovered that there was a particular green caterpillar found in abundance in the large tarweed patch. After research I learned that the owlet moth (Heliothodes diminutiva) uses tarweed as it’s host plant, eating the reproductive organs (i.e flowers) of the plant as it grows, sometimes sterilizing the plant entirely. Tarweed seeds were also historically used as food by the local indiginous people; documented use of tarweed is known for the Hupa, Takelma, and Shasta tribes. Examples of how tarweed seeds were historically used include:

• Seeds parched and pounded into flour.
• Seeds roasted with hot coals, pounded or rolled into flour.
• Pulverized seeds eaten as a dry meal.
• Seeds used to make pinoles, where seeds were roasted and eaten alone or mixed with manzanita berries, acorns and pine nuts.
• Ground tarweed seeds mixed with ground hazelnuts and camas.

Many people are familiar with the use of camas and acorns as indigenous food sources; however, small seed crops, such as wild grass and tarweed, were also vitally important to the indigenous diet. The Klamath-Siskiyou tribes developed extensive land management practices to enhance all wild crops they relied upon. Techniques such as burning, pruning, tilling, weeding, and selective harvesting were most likely used. Additionally, the act of harvesting itself helped spread seeds for subsequent crops.

In 1841, Titian Ramsay Peale of the Wilkes Expedition, traveling through what is now Ashland, OR, wrote in his journal, “Indian signs were numerous, though we saw but one, a squaw who was so busy setting fire to the prairie and mountain ravines that she seemed to disregard us….She had a large funnel shaped basket which they all [women] carry to collect roots and seeds in.” It is assumed that this woman probably was burning to obtain tarweed or grass seeds, or at least to enhance their future growing conditions. George Riddle, who settled in southern Oregon in 1851, described in his book, History of early days in Oregon, tarweed gathering among the Takelma-speaking Cow Creek Indians along the South Umpqua River: “During the summer months the squaws gather various kinds of seeds of which the tar weed was the most prized…. When the seeds were ripe the country was burned off. This left the plant standing with the tar burned off and the seeds left in the pods. Immediately after the fire there would be an army of squaws armed with an implement made of twigs shaped like a tennis racket with their basket swung in front they would beat the seeds from the pods into the basket. This seed gathering would only last a few days and every squaw in the tribe seemed to be doing her level best to make all the noise she could, beating her racket against the top of her basket. All seeds were ground into meal with a mortar and pestle.”

Consider encouraging this wildflower if it already exists on your property or in your area, or plant some seeds for the future. As an annual it is really easy to grow from seed and self sows in open soil! The historical and ecological value of tarweed could enhance your own land or local ecosystem. Tarweed would be ideal for gardeners or restoration practitioners attempting to mimic a native prairie and/or grassland landscape. Tarweed seed is best planted in late winter to allow for a deep root system to develop before summer; however, in a garden setting infrequent summer watering will be tolerated by this species .