Tussilago contains livertoxic pyrrolizidine alkaloids. Read more here. -Henriette
A COMMON wild herb, of excellent virtues, but so different in the spring and summer, as that it is scarce to be known for the same. The flowers appear in spring without the leaves; they grow on stalks six or eight inches high, round, thick, fleshy, and of a reddish colour, on which there stand a kind of films instead of leaves. The flowers grow one at the top of each stalk; they are yellow, and as large as those of the dandelion, and like them.
The leaves come up after these are decayed, they are as broad as ones hand, roundish, and supported each on a thick hollow stalk, they are green on the upper side, and white and downy underneath. The flowers are not minded, these leaves only are used.