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•Toxic larkspurs (Delphiniumspecies) cause large economic losses from cattle deaths, increased management costs, and reduced utilization of pastures and rangelands.•Larkspur toxicity to cattle can vary by geographic location due to toxic alkaloid content.•Larkspur alkaloid chemistry can be used to predict plant toxicity.•Cattle breeds differ in their susceptibility to larkspur poisoning.•As cattle age from yearlings to two-year olds, they become less susceptible to larkspur.•Heifers are three times more likely to be poisoned at the same dose of larkspur alkaloids than either bulls or steers, suggesting that they must be managed differently on rangelands where larkspur is present.

•Poisonous plants on western North American rangelands have historically been troublesome to livestock producers.•Research on toxic plants was initiated by the United States Department of Agriculture in the late 1890s to solve problems for the livestock industry.•The United States Department of Agriculture Agricultural Resource Service Poisonous Plant Research Laboratory in Logan, Utah continues to provide research-based solutions to poisonous plant problems besetting livestock producers, hobby farmers and small holders, veterinarians, and extension personnel.•Principal plants of current research interest include larkspur, lupine, locoweed, selenium accumulating plants, pyrrolizidine alkaloid-containing plants, and ponderosa pine.

•Western juniper trees can cause late term abortions in cattle, similar to ponderosa pine trees.•Results from this study demonstrate that there is no difference in the labdane acid (the abortifacient compounds) content of western juniper trees throughout the year, or from year to year.•Consequently the abortifacient risk of western juniper trees should not vary throughout the year, or from year to year.•Producers who winter cattle in rangelands with western juniper trees should take similar precautions to prevent late term abortions as they would with ponderosa pine trees.

On the Ground•Toxic larkspur (Delphinium species) cause large economic losses from cattle deaths, increased management costs, and reduced utilization of pastures and rangelands.•We recommend that you obtain a risk assessment for larkspur on your range before turning out the cattle. Submit samples to USDA–ARS Poisonous Plant Research Laboratory for chemical evaluation at no charge. Information is available at: http://www.ars.usda.gov/main/site_main.htm?modecode=54-28-20-00.•Selection of cattle resistant to larkspur poisoning could reduce cattle losses and improve rangeland utilization.•The use of genetic-based herd management decisions can provide a tool for livestock producers to improve their profit margin and enhance the economic sustainability of rural American communities.

•The bark, leaves, and berries of western juniper trees in Oregon can cause abortions in late-term pregnant cattle.•The percentage of the abortion-causing compounds varied from tree to tree in a location, as well as between locations across Oregon, but did not appear to vary across time.•Cattle producers who winter cattle in pastures with western juniper trees should take cautions such as denying late-term pregnant cattle access to these pastures, providing adequate feed and shelter, maintaining pregnant cattle in good body condition, changing calving schedules to late spring or early fall, and, if abortions do occur, seeking veterinary care for any postpartum complications.