Delphinium andersonii (Anderson larkspur) is a perennial forb on semi-arid rangelands, and population density is related to cattle deaths. A multi-year study was initiated in 2011 to measure toxicity, plant density and life history of D. andersonii populations in southern Idaho. In 4 out of 7 years, essentially no plants emerged and flowered because of drought conditions. During the 3 years when some plants emerged and flowered, plant densities were 2, 7, and 10 plants/m2.� Previous research has shown that plant densities greater than 5 plants/m2 pose a serious threat to grazing cattle. Approximately 8% of the marked plants remained dormant for 2-4 years, then emerged when precipitation was favorable.� Late winter and early spring precipitation appear to drive D. andersonii populations.�� Persistent drought is fatal to some plants, but dormant plants may re-emerge when sufficient, timely rainfall occurs.
Oral presentation and poster titles, abstracts, and authors from the Society for Range Management (SRM) Annual Meetings and Tradeshows, from 2013 forward.