The Arrowleaf ragwort (Senecio triangularis) belongs to Asteraceae (the Aster family). It is a perennial herb that is distributed from Alaska to western Canada and the western United States. This herb grows in meadows, stream banks and other moist places in the mountains, and up to a height of 30-150 cm. The stem is single and erect. The leaves are triangular, short petioled or sessile, and with acute denticulate edges. Few to numerous yellow flower-heads bloom in small cluster at top from June to September. The flower-head includes 8 ray flowers toothed at tips, 40 disk flowers in center.