Ranunculus acris is a species of flowering plant in the family Ranunculaceae, and is one of the more common buttercups across Europe and temperate Eurasia. Common names include meadow buttercup, tall buttercup and giant buttercup.
This species is variable in appearance across the world. It is a somewhat hairy plant that has ascending flowing stems bearing glossy yellow flowers about 25 mm across. There are five overlapping petals borne above five green sepals that soon turn yellow as the flower matures. It has numerous stamens inserted below the ovary. As with other members of the genus, the numerous seeds are borne as achenes. This and other buttercups contain ranunculin, which breaks down to the toxin protoanemonin, a chemical that can cause dermatitis and vomiting.
The plant is an introduced species across much of the world. It is a naturalized species and often a weed in parts of North America, but it is probably native in Alaska and Greenland. In New Zealand it is a serious pasture weed costing the dairy industry hundreds of millions of dollars. It has become one of the few pasture weeds that has developed a resistance to herbicides.
In horticulture the species may be regarded as a troublesome weed, colonising lawns and paths. However, it may be a welcome feature of wildfower meadows. The double-flowered cultivar R. acris 'Flore Pleno' has gained the Royal Horticultural Society's Award of Garden Merit.
- USDA Plants Profile: R. aestivalis.
- Invasive Weeds of King County, Washington
- Flora of North America
- Bourdôt, GW; Saville DJ (2010-08-31). "Giant buttercup - a threat to sustainable dairy farming in New Zealand". Proceedings of the Australasian Dairy Science Symposium: 355–359.
- Cronshaw, Tim (18 May 2012). "Profit-strangling weed immune to hebicides". The Press.
- "RHS Plant Selector - Ranunculus acris 'Flore Pleno'". Retrieved 30 May 2013.
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