Weed of the Week - Tall Buttercup
Weed Of The Week #6
Tall Buttercup (Ranunculus acris)
Noxious Under Alberta's Weed Control Act
Submitted By Kelly Cooley, CoolPro Solutions
Another unfortunately very common and quite successful non-native invasive weed here in Southwest Alberta is the long lived perennial Tall Buttercup AKA Meadow Buttercup, often seen flowering together with our previous Weed Of The Week, Oxeye Daisy.
Tall Buttercup is a water-loving species, its presence often indicative of underground springs, as wetlands are its preferred habitat. This preference and its intense competitiveness choke out many other desirable native wetland plant species. Mainly spreading by seed, Tall Buttercup's thin stems and basal foliage can go unnoticed prior to the emergence of their distinctively bright five petalled flowers, which appear shiny on the petals top sides and often with tufts of thin hair on the petals bottom sides (see photos). Thin stems and lower leaves are also hairy. It is important to note the shape of the leaves, which are often compared to a crow's foot - deeply lobed and shaped like the palm of a hand(see photos). There is a native buttercup which is similar, but can be distinguished by the leaves (see photo). Tall Buttercup grows from a thick rootstalk, which is capable of sending out short rhizomes to form new daughter plants.
Tall Buttercup's sap contains a glycoside that is toxic to many livestock, particularly cattle, but poisoning is rare because they generally refuse to graze it, aiding its survival and spread. It is capable of dominating the species mix in wetter foothills pasture land and natural areas, particularly those that are heavily grazed, and spreads readily down watercourses and up disturbed areas such as cut lines, human trails & roads, and animal trails. Tall Buttercup invades forage crops as well, particularly grass-based hay. Fortunately, the toxic sap seems to dry up in cured hay, greatly reducing the risk of livestock poisoning.
Mowing continuously to prevent seed production does help, but will not control perennial regrowth. This species may be controlled by using selective broadleaf herbicides, focusing on pre-flowering plants throughout the growing season. This can be difficult due to the wet conditions Tall Buttercup likes to grow in. Periods of dry weather, even drought conditions that seem to be threatening this year, provide opportunities for landowners to treat usually wet areas dominated by Tall Buttercup. More information on this aggressive invader can be found in the Tall Buttercup fact sheet from the Alberta Invasive Species Council, as well as in the Montana Weed Control Association video noted below (or in the comments). You can report this invader yourself using the Alberta Invasive Species Council's free EDDMapS application on your mobile device. For local Tall Buttercup control options, please contact our Agricultural Fieldman at 403-339-8741.
Kelly Cooley, CoolPro Solutions
Todd Green, County of Newell
Alberta Invasive Species Council
Dave Brink, Montana State University Extension
Tall Buttercup Video: Montana Weed Control Association
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