GROW: Do We Really Need This Weed?
Have you ever asked yourself why there are certain weeds, insects and slugs? Often we conclude that they serve no purpose but, of course, Mother Nature is a complex system where every living thing serves the whole in some way. Guest author Tara Woods Baker shares a rare look at an even rarer plant and offers insight on what it could teach us.
On the cracked clay soil around the runways of the Klamath City Airport, some straggly weeds are dispersed thinly on the mostly bare fields. These are Applegate’s milk-vetch (Astragalus applegatei). They are low to the ground, maybe a foot tall, with 20-50 stiff stems and small leaves. In the summer, the stems might have tiny white to pinkish flowers for a short time, which then turn to small seedpods. It is not a very pretty plant and easily missed in the landscape.
Applegate’s milk-vetch was thought to be extinct, but a small population of the plants was found in 1983, and so, it was resurrected. This plant grows in only six different plots around the city of Klamath Falls, Oregon, within a high desert habitat. In all the world, there is no other species just as this one. So it is protected. Applegate’s milk-vetch (Astragalus applegatei) is a special weed, designated as an endangered species with special rights and protections. Multiple agencies are monitoring it, searching for new populations, studying its reproduction and its habitat. In all the world, only about 70,000 plants survive. But looking at it, it is difficult to understand why we even want to save it.
As a biologist, I am trained (and train my students) to answer, ”We want to save it to increase biodiversity.” But what does that really mean when looking at the cost of trying to save an ugly, seemingly useless weed? Even Applegate’s milk-vetch doesn’t seem to want to survive. It has a very low fertilization ability: of 10 possible seeds, only about 3 usually fully develop.
A Weed that Seems to Strive Toward Extinction
Scientists and horticulturists have tried to grow the plants in the lab, then transfer them back to their original region, but with poor success. First, lab assistants need to coddle the miniature seeds by rubbing each with sand-paper. Next, these fussy plants do not grow in healthy, robust soil until it is mixed with a dollop of poor soil from its original sites. Finally, the straggly plants begin to grow. But even then, Applegate’s milk-vetch refuses to participate in its own conservation plan. Of approximately 1000 healthy, lab-started plants replanted in the natural habitat around Klamath Falls, only about 10 survived and reproduced. Is it worth it? Even the plants seem to strive towards extinction.
We thought Applegate’s milk-vetch had gone extinct until 1983; and we survived. The world did not come to an end. No one really missed it. So could we survive if it failed and went extinct for real?
Yes, we could survive, but our world will be much less without this ugly little plant. Applegate’s milk-vetch grows in some of the worst soils known. The soil is strongly alkaline (high pH), so much so that the Applegate’s milk-vetch is often the only plant species in the area. The surface of these soils is cracked and white-crusted with calcium carbonates during times of normal, seasonal drought.
In the winter and spring, the soils are water-logged, as the high clay content holds in moisture. Plants that will grow in this habitat are tough. The secret to their ability to withstand such awful habitats is within their DNA. Can we learn these secrets and apply them so we can grow agricultural plants in harsh environments? Can we learn from their DNA how to use less fertilizers and irrigation?
One of the most important findings that has come from studying this milk-vetch is that it has a required symbiotic relationship with fungus and nitrogen-fixing bacteria. Without this enter-twined system, the plants cannot grow, even when planted in nutrient-dense soil. The specific species of symbiotic organisms have not been determined yet, but they are not included in current commercially available mixes. They are new and unidentified, and they allow a plant to thrive in a hostile habitat. It is so important that we learn more about these species. They might allow farmers to grow plants in high deserts where food has been scarce, like areas in Africa and Asia with similar environments. Maybe even on Mars, where the soil is poor, alkaline.
It's About Relationships
So, Applegate’s milk-vetch is not very impressive on its own. It’s an ugly, straggly weed. However, when we look closer, we can appreciate its special qualities. It grows in an equally ugly habitat. It survives when most other plants fail. It has symbiotic relationships it needs to live there. If we allow the plant to go extinct, we may be letting these unidentified fungi and bacterial species go extinct as well. If they are lost, we may never learn how they live where almost nothing else does.
As our climate changes, we will be experiencing habitat changes we cannot fully predict. As much as possible, we need to learn how to survive and grow foods in as many possible environments as possible. Applegate’s milk-vetch has information about how to live in a high desert with alkaline, arid, and seasonally water-logged soil. It may not be pretty, but it can live where so many others cannot. We do need this weed.
Barroetavena, Carolina, et al. Mycorrhizal status of the endangered species Astragalus applegatei Peck as determined from a soil bioassay. Mychorriza. Sept. 1998. 8(2):117-119. https://link.springer.com/article/10.1007/s005720050222
Larson, Ron. Applegate’s Milk-Vetch (Astragalus applegatei) The Story of One of Oregon’s Rarest Plants. 2013. https://www.klamathbasinnps.com/Resources/Documents/Applegates%20Milk-Vetch%20Presentation%20Dec%202013.pdf
USFWS (U.S. Fish and Wildlife Services). 2009. Astragalus applegatei(Applegate’s Milk- vetch) 5-year review summary and evaluation. U.S. Fish and Wildlife Service, Klamath Falls, Oregon. 26 pp. Available at http://ecos.fws.gov/docs/five_year_review/doc2380.pdf
Tara Woods Baker's Bio
I received my Ph.D. in Zoology and Genetics from Iowa State University in 1997, then began teaching at a small liberal arts college in far-away Oregon. My family and I were immediately enamored by the beauty in our new home state. We have explored it by hiking, backpacking, camping, kayaking, and driving. From the Pacific with its tidepools and temperate rainforests to the high chaparral and desert on the east-side, we have peered into many of Oregon’s nooks and crannies. I am currently an educator at a community college, and also a continuous student of the world around me. I am able to attend the many fantastic science seminars in the Portland area sponsored by great organizations, like OMSI’s Science Pub, Science on Tap, Oregon Zoo, Hoyt Arboretum, and more. You will find me at seminars, at pursuing books at a Powell’s Bookstore, looking for agates on the beach, counting amphibian egg-masses on citizen science surveys, pointing a camera at an eagle on a limb, paddling my kayak in a nearby river or lake, or dusting the trails up on Mount Hood.