Word Study
senecio
CIDE DICTIONARY
senecio, n. [L., groundsel, lit., an old man. So called in allusion to the hoary appearance of the pappus.].
A very large genus of composite plants including the groundsel and the golden ragwort. [1913 Webster]
OXFORD DICTIONARY
senecio, n. any composite plant of the genus Senecio, including many cultivated species as well as groundsel and ragwort.
Etymology
L senecio old man, groundsel, with ref. to the hairy fruits
For further exploring for "senecio" in Webster Dictionary Online