A study of poisonous drymaria on southern New Mexico ranges

TitleA study of poisonous drymaria on southern New Mexico ranges
Publication TypeJournal Article
Year of Publication1937
AuthorsLittle, Jr. E.L.
Date Published1937
Keywordscattle, harmful plants, poisonous drymaria, southern New Mexico
AbstractAmong the harmful plants that grow on clay (adobe) soils on ranges of southern New Mexico, the most poisonous for cattle are dwarf summer annuals of the species Drymaria holostcoides Bentham (D. pachyphylla \Woot. and Standl.). Of more than a dozen species of J)rvmaria occurring in Central America, Mexico and southwestern United States, members of only the species named are known to be toxic. These plants have been found in southern New Mexico, southwestern Texas, southeastern Arizona, and Mexico. Because of the great number of deaths of range cattle caused by eating these poisonous plants, a study of them was made by the author in 1934 and 1935 with a view to determining feasible methods of eradication and how livestock losses might be reduced. These investigations were made at the Jornada Experimental Range, U.S. Forest Service, near Las Cruces, New Mexico. Discovery of these plants as poisonous is recent. In 1922, the New Mexico Agricultural Experiment Station and the Bureau of Plant Industry, U.S. Department of Agriculture, began a cooperative study of these plants. Lantow ('29), of the former institution, demonstrated their extreme toxicity to cattle and sheep in feeding experiments from 1923 to 1927 and found all parts of the plants above ground to be poisonous at all stages of growth. Because of the unpalatability of the plants, forced feeding was necessary. Campbell ('31) showed poisonous drymaria to be a pioneer weed in plant succession on clay soils, and made germination tests of the seeds. Mathews ('33) conducted additional feeding experiments in southwestern Texas in 1932 and determined lethal doses. He reported that the plants caused death in a cow when they were eaten at the low rate of 0.4 percent of body weight, in a sheep at 0.6 pe cent, and in a goat at 0.97 percent. The toxic principle has not been determined.