NEBRASKAland Magazine is dedicated to outstanding photography and informative writing with an engaging mix of articles and photos highlighting Nebraska’s outdoor activities, parklands, wildlife, history and people.
Issue link: http://mag.outdoornebraska.gov/i/977334
MAY 2018 • NEBRASKAland 45 beetle and a seed chalcid wasp, for example, eat the seeds (as they develop within the pods) of two-grooved milkvetch and princesplume with no apparent ill affect. In a seleniferous area of Colorado, a species of diamondback moth was recently discovered that lays its eggs on and "voraciously feeds" on princesplume leaves. Since the distressing experience in our house, I have come to appreciate the odor of alkali milkvetch. When near plants in open prairie, I find their smell light and pleasant, not pungent. A whiff of selenium also reminds me of the plant's ingenuity – the ability to accumulate a toxin to protect against the hazards of nature. By the way, now when collecting alkali milkvetch seedpods, I store them in the shed. ■ Alkali milkvetch in flower on a prairie hillside near Sugar Loaf Butte in Sioux County. In his book Dakota Flora – A Seasonal Sampler, South Dakota botanist Dave Ode relates the following story of how scientists unravelled the mystery of selenium poisoning in livestock. In the late summer of 1856, several cavalry companies arrived at the newly established Fort Randall on the Missouri River in Gregory County, South Dakota (located about 15 miles west of our present day farm). Over the next few months, many of their horses became ill, some died; symptoms included loss of hair from their manes, hoof sloughing and swelling of the throat and jaw. From this incident, the Fort's medical doctor T.C. Madison wrote the first clinical description of a type of selenium poisoning which later became known as alkali disease. During the late 1800s, ranchers and farmers in central South Dakota and a few other areas of the state continued to lose livestock to the disease; they blamed alkali water – thus the name "alkali disease." Researchers at South Dakota State College spent years proving that alkali water was not the culprit, but they still could not pinpoint the cause of the disease. With the onset of the severe drought of the early 1930s, grass forage became limited and livestock were forced to consume selenium-accumulating plants. The disease worsened. Finally in 1934, scientists determined that selenium poisoning was the cause of alkali disease and another livestock disease known as the blind staggers, where afflicted animals walk with an unsteady, staggering gait, often running into objects and appearing blind. Acute selenium poisoning in livestock from eating alkali milkvetch and other obligate selenophiles is uncommon because the plants are so unpalatable. Chronic selenium poisoning of the alkali disease type results from animals ingesting grasses and other plants containing moderate levels of the element. Alkali Disease