This section is from the book "A Guide To The Poisonous Plants And Weed Seeds Of Canada And The Northern United States", by Robert Boyd Thomson, H. B. Sifton. Also available from Amazon: A guide to the poisonous plants and weed seeds of Canada and the northern United States.
The Bloodroot, Sanguinaria canadensis L., is another native drug plant, containing sanguinarin which in small doses is a tonic, but in larger quantities exerts a severe irritant effect, with nausea and burning sensations in the mucous membranes, followed by vertigo and insensibility. In the natural state it is not eaten, for the taste is exceedingly acrid, and the orange red juice is repulsive.
It is among the earliest of our spring flowers and is found in rich woods of the eastern half of the continent. The heavily-veined and lobed leaf is at first folded about the flower bud, showing only its greyish-green, under surface. The two sepals fall off as the flower opens, and the eight white petals soon follow. The shining brown seeds are contained in slender green pods. The thick, red perennial rootstock is rich in alkaloids.
The Greater Celandine, Chelidonium majus L., has effects that are similar to those of Bloodroot. It also is rarely or never eaten by stock.
It is a brittle plant, one to two feet tall, with deeply lobed leaves and small yellow flowers. The two sepals fall off when the flower opens, leaving four yellow petals. The juice is deep yellow, turning red on exposure to air.