Item Type text; Article
Authors James, Lynn F.
Citation James, L. F. (1983). Poisonous plants: Locoweeds. Rangelands, 5(5), 224-225.
Publisher Society for Range Management
Journal Rangelands
Rights Copyright © Society for Range Management.
Download date 23/09/2021 12:31:30
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Link to Item http://hdl.handle.net/10150/638453 224 Rangelands5(5), October 1983 Poisonous Plants: Locoweeds
Lynn F. James
The locoweeds, certain species of the generaAstragalus and Oxytropis, are one of the most destructive groups of plants poisonous to livestock. There are over 300 speciesof Astraga/us in North America. The taxonomy of this group of plants is difficult and often requiresthe help ofa trained taxonomist for positive identifi- cation. For many years the genera Oxytropis was included withAstra ga/us. Many feelthat the basis for the separationof the Oxytropis from the Astraga/us was inadequate. Due to this close taxonomic relationshipand becauseof the similar- ity in the toxic effects of these two genera on livestock, we shall consider them together. The locoweed, Astragalus lentiginosus. Description If animals graze locoweed for a considerable time, or stemmed they Astraga/us species may be annual perennial, become emaciated and may become recumbent and die. which a of sta- or stemless herbs display diversity growth, Recoverydepends on the extentof intoxication. Animals that ture, and general appearance.The leaves are alternate and have become continue to show of The flowers are The fruit poisoned may signs poi- pinnately compound. leguminous. when under stress. Such animals recover a of various and surfaces that soning placed may is legume pod sizes, shapes to the extent they can reproduce but horsesthat are used for contains one to seeds. One of the many kidney shaped riding or draftpurposes become useless and should be dis- remarkable features of Astraga/us is that all species differ of. from one another in the form or structure of the fruit. The posed Once animals havestarted tograze locoweedthey seem to seeds of some desertAstra ga/us may retaintheir viability for search for it and attimes it at theexclusion ofother and to 40 or graze up years longer. oft times more desirable forage. Oxytropis may be distinguished from Astraga/us by the The locoweeds are toxic all of keel most of the which is during stages growth and (lower petal) Oxytropis prolonged afterthey becomedry. Livestock must grazethe locoweeds into a long distinct point. The keel petal on Astraga/us is over an extended of time before intoxication occurs. blunt. period The time is closely related to the rate at which theygraze the Toxic Principle plants. Usually by the time intoxication is obvious, damage Not all species of Astraga/us and Oxytropis are toxic. has been done to the animal. Those that are can be divided into three general groups as follows: (1) about 21 speciesof Astragalus have the ability to accumulate seleniumat levels that render them toxic, (2) the nitro-containingAstraga/us that have as their toxicconstitu- ent the 13-D-glycoside of 3 nitro-1-propanol or 3 nitro-1- propionic acid (these plants produce chronic or acute intoxication depending upon the rate atwhich they are con- sumed), and (3) locoweeds have been shown to contain an indolizidine alkaloid called swainsonine which is now thoughtto be the toxin in this group of Astraga/us. Toxicity The name loco is derived from the Spanishword for crazy and is used to describe the particular intoxication and the group of plants causing the condition. Many use the term loco, incorrectly, to describe all Astraga/us species Thefollowing is a partial listof the locoweeds:A. lentigino- sus, A. mol/issimus, A. wootofu, A. pubentissimus, 0. seri- cea, and 0. /ambertii. The locoweeds cause numerous problems in livestock, including neurologic effects, repro- ductive alterations, emaciation, and habituation. Neurologi- cal problems are reflected by signs of poisoning which includedepression, slowirregular gait, rough haircoat, dull appearing eyes, muscular incoordination, and excitement when stressed. The reproductive consequences include abortions, birth defects, birth of small offspring, and altera- tions in spermatogenesisand oogenesis. The locoweed, Oxytropis sericea. Rangelands 5(5), October 1983 225 Conditions of Poisoning Prevention The desert species of the locoweeds usually germinate Maintaining ranges in a good condition with a variety of and grow duringwarm moist conditions of late summerand desirable forage species is the first step in preventing loco- fall. The plant often remains green during the late fall and weed poisoning. Livestock should be preventedfrom start- winter. When the locoweed is green and other forage is ing to graze the locoweed plant. This may involve dormant and dry, locoweed increases in palatability and supplemental feeding programs, or development of loco- animals may start grazing it. They may also start grazing weed free pastures.If livestock start grazing locoweed,they locoweed during periods of drought when littleother forage should be movedfrom the areas infested with theplants; only is available, especially if the locoweed is green. However, the offending anmals may need to be moved. livestock have become intoxicated on dry plant material. The locoweed Oxytropis sericea has been successfully Livestock may start grazing locoweedsfor no apparant rea- controlled in some areas by spraying it with 2 lb of the low son. The locoweeds are not considered to be especially volatile ester of 2,4-D. palatable. Selected Reading James, L.F., W.J. Hartley, and K.R. Van Kampen. Syndromes of Locoweed Poisoning.Amer. Jour. Vet. Med. 178:146-150. 1981.
A New Year • New Programs ... NewChallenges • New Opportunilies
During the Gulfportmeeting we presenteda composite of B. We will recognize the top three members who have ideas from members and the staff to the Board of Directors. recruited the greatestnumber of membershipsother than The following are some of the ideas we present for your student memberships. review and support. C. Wewill recognize the top3 student or youth organiza- Rememberthat your committee, the staff, and the Board tionswith the greatestpercentage increasein membership. can develop programs and present ideas and approachesto Guidelines for the awards will be sent to the Sections and help increase membership. published in the next Rangelands. Membership is and always will be a Section respon- 6. The Denver Staff is reinstating the program of yearly sibility. Only with your cooperation, hardwork, and stickers for your membership certificates. Stickers dedication can we increase membership. Only with for the years 1980, 1981, 1982, and 1983 are also available to the The 1984 membership growth can we increase theawareness of upon request Membership department. sticker will be enclosed with 1984 Dues Notice. the importance ofthe use of the range resource. proper 7. We that information be The are some ofthe we to strongly suggest membership following programs hope pursue displayedat all SRMFunctions and thatstrong efforts beput in the 1984membership year. forward to solicit new membersat these functions. for the 1. We plan to bill all members on September 8. We would to all members toconsider life mem- Another will besent out in December. appeal upcoming year. billing bership in SRM—a real savings to the member and also a Reminderswill be mailed on January 20 and March 20. financial boost for 2. The staff has a list of all members your Society. completed dropped 9. We encourage presenting membershipinformation and for 1980, 1981, 1982. These people will also receivethe bil- in all Section how reminders newsletters. lings mentioned in item 1. (Mightbe surprised by many You all if new with SAM. have heard that each of us were to solicit a rejoin who are already acquainted member we could double our members. In 1983we 3. The and Section officers will work stayed staff, committee, even. We dropped 20% in old members and solicited 20% to of all from USFS, SCS, together compile listings people new members. Sadly this is the story for the last several Extension, BLM, BIA, state fish and game, and others who years. have interests in range. We hope to workhard to seethat all of Thisyear let's workto keep all ofour presentmembers and these people are contacted about SRM and the benefits work for a 25% increase in new members. membership. By workingtogether we can do this. Ittakes the coordinated 4. We to establish an Member- plan Industry Sustaining effort of the society, the BOD, the staff, your membership and have this in for 1985. Will ship Category place probably committee and the Section membership committees and workon some for 1984. people each and every one of us to get this important job done. 5. We plan to establish recognition plaques to recognize different groups for increasesin membership. We will recog- Let's make 1984 the year SRM membership has a third winners in each of nize the first, second, and place marked and lasting increase. these categories. Your Membership Committee A. The Section with the of increase greatest percentage -Art Armbrust, Chairman, membership.