Asteraceae
Daisy Family
Silphium laciniatum L.
- Stem: perennial; 4’ to 6’ tall; often several stems from one rootstock; hairy early in the season, somewhat woody late in the season.
- Leaves: alternate; deeply, pinnately lobed with five to seven pairs of lobes; blades 12” to 24” by 6” with leaf stalks on the lower leaves; margins of the lobes sometimes with large teeth; rough above and below.
- Inflorescence: one or two flower stalks with numerous heads widely scattered; heads on short, hairy stalks, 1/2” to 1” long.
- Heads: yellow rays 1” by 1/4”; disk 1” to 1 1/2” across, the flowers yellow; head 3” across; fillaries oval with sharp, spreading tips, 1” long with hairs on margins and outer surfaces; flowering from early July to early August.
- Fruits: “seeds” (fruits) flat, oval, concave; about 3/8” long; no plume; only the outer flowers setting fruit; fruiting begins in mid-July.
- Habitat: infrequent on upland prairies to dry, sandy, and wet prairies.
- Notes: Compass plant is named for its tendency to orient its leaves facing east and west, perhaps as a cooling mechanism on hot summer days. As a result the plant gives a rough idea of the north-south axis but no clue as to which direction is north and which is south.
- Bibliography from Biodiversity Heritage Library
- Vascular Plants of Iowa
Can be found in these counties:
