Buttercup (Ranunculus spp.)
| Description | Distribution | Conditions of poisoning | Control | Toxic principle | Clinical signs | References
The small-flowered buttercup is an erect, often widely branched smooth herb 6 inches to 2 feet tall, with a hollow stem. It has two kinds of leaves: petioled basal leaves that are roundish and have scalloped edges; and alternately placed stem leaves that are stalkless, deeply divided, and made up of about 5 narrow lobes, often 3-pointed. Its flowers are yellow, are 1/4 inch wide or less, and have 5 petals, which are shorter than the 5 green sepals. After the flowers wither, numerous seeds form globose heads at the tops of the flower stalks.
The cursed buttercup (Ranunculus sceleratus L.) is similar to the small-flowered buttercup but has divided basal leaves. Its stems are hollow. The hooked buttercup (Ranunculus recurvatus Poir.), so-named because of its hook-tipped seeds, has long yellow petals that form a flower 1 inch wide. The swamp buttercup (R. septentrionalis Poir.) has 3-lobed leaves and bright-yellow flowers 1 inch or more wide.
The buttercups named above occur as frequent to common plants throughout the state. The small-flowered buttercup, often a troublesome weed, may be found in any location that is not very sandy or wet. The cursed buttercup is limited to the northern third of the state, where it may be abundant in ditches and springy places as well as in ponds. The swamp buttercup grows in wet woods everywhere in the state.
Several other kinds of buttercups, less abundant or less widely distributed, may be seen in other habitats or from place to place. The tall buttercup (Ranunculus acris L.), to which poisoning of stock is commonly attributed, occurs in northern and central Illinois as a plant introduced locally along highways and railroads.
Buttercups generally inhabit moist areas. Animals allowed to graze in woods, in wet meadows, and by ditches and streams browse the buttercups with other succulent plants. All animals are susceptible to buttercup poisoning, but cows are most often poisoned. Dried buttercups, however, are not poisonous; therefore buttercup-infested hay can be fed without danger.
Animals should not be grazed in pastures heavily infested with buttercups, especially when other herbage is scant or dry. Buttercups are hard to destroy because of their tendency to inhabit moist and wet places. Mowing the plants each year before they produce seed will tend to keep them from increasing and may eventually destroy them.
Ranunculus spp. contain the glycoside, ranunculin from which the poisonous principle, protoanemonin is released when the plant is crushed by virtue of enzymatic action which is activated by crushing. Protoanemonin is a volatile, yellow oil with a lactone moiety which is extremely prone to undergo spontaneous polymerization to yield the innocuous anemonin. Protoanemonin is a bitter tasting oil.
Buttercup poisoning causes cows to give less milk and may cause the milk to be bitter and red tinted. Severe poisoning brings on colic and diarrhea, with black foul-odored feces, nervousness, twitching of the ears and lips, difficult breathing, and eventually convulsions. The symptoms shown by horses and sheep are similar, but poisoned sheep are likely to fall suddenly. Pigs suspected of tall-buttercup poisoning have shown paralysis but not much digestive disorder.
Ranunculus entry in Wikipedia
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