a tall plant, Silphium laciniatum, of central North America, that has yellow flowers and lower leaves that tend to align themselves at right angles to the strongest light, esp in a north-south plane: family Asteraceae (composites)
2.
any of several similar plants
compass plant in American English
US
1.
a coarse plant (Silphium laciniatum) of the composite family, with large, bristly leaves and heads of yellow flowers, found on the prairies of central U.S.: the leaves reputedly point in a north-and-south direction
2.
any of various other plants whose leaves supposedly point to the north and south