Ageratina Altissima or

Ageratina Altissima or

Ageratina Altissima

Plants are upright or sometimes ascending, growing to 1.5 metres (4.9 ft) tall, producing single or multi-stemmed clumps in mid to late summer and fall. The flowers are a clean white color and after blooming, small seeds with fluffy white tails are released to blow in the wind. They are found in woods and brush thickets where they bloom mid to late summer or fall. The species is adaptive to different growing conditions; it is found in woods and brush thickets and also in shady areas with open bare ground, and can be weedy in shady landscapes and hedgerows. There are two different varieties: Ageratina altissima var. altissima and Ageratina altissima var. roanensis (Appalachian white snakeroot); they differ in the length of the flower phyllaries and shape of the apices.



The common name of this species derives from the erroneous belief among early settlers that the bitter rhizomes were beneficial in the treatment of snakebites. In fact, the foliage and rhizomes are highly toxic, causing fatalities from 'Milk Sickness' because the toxins can pass through the milk of dairy cattle to humans. White Snakeroot has been reassigned recently to the genus Ageratina, although it is still often referred to as Eupatorium rugosum. Normally, White Snakeroot is largely hairless, although some authorities describe a pubescent variety of this species. White Snakeroot resembles many of the white-flowered Eupatorium spp. (Bonesets), but these different species can be distinguished from each other by the appearance of their leaves. Among the species in this group, White Snakeroot has the broadest leaves; its lower leaves are cordate or broadly ovate, and these leaves have long petioles. White Snakeroot usually occurs in and around shady woodlands, while many of these other species are found in prairies and sunny wetlands.

White snakeroot (Ageratina altissima) is a sporadically toxic plant that causes trembles in livestock and milk sickness in humans that drink tainted milk. The putative toxin in white snakeroot is tremetone and possibly other benzofuran ketones, even though it has not been demonstrated in vivo. Toxic white snakeroot was dosed to goats, and they developed clinical signs of poisoning, exercise intolerance, significant increases in serum enzyme activities, and histological changes. Tremetone and the other benzofuran ketones were extracted with hexane; the extracts and residues were analyzed for tremetone and dosed to goats at tremetone and benzofuran ketone concentrations similar to the original plant material. However, none of the dosed goats developed the disease. The results demonstrate for the first time that white snakeroot is a potent myotoxin in goats and that other compound(s), which may be lost or modified during the extraction process, could be involved in causing trembles and milk sickness. (Source: pubmed.ncbi.nlm.nih.gov)



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