compass plant

(Silphium laciniatum)

Conservation Status
compass plant
  IUCN Red List

not listed


NNR - Unranked

SNR - Unranked


not listed


Compass plant is an erect, perennial forb that rises on usually a single stem from a deep, woody taproot that can extend 15 into the soil. It can be 3 to 6½ in height, but is usually no more than 8 tall. It is a long-lived plant, sometimes surviving up to 100 years.

The stem is erect, stout, light green or medium green, round in cross section, and unbranched below the inflorescence. It is moderately covered with relatively long, white hairs and also with minute, usually gland-tipped hairs.

Basal leaves are egg-shaped in outline, 12 to 24 long, and 6 to 12 wide. They are rough to the touch, thick, and leathery. They are deeply cut almost to the midrib into 3 to 15 primary lobes (pinnatifid) which are sometimes again lobed (bipinnatifid). The primary and secondary lobes are oblong to oblong triangular. They taper to a sharp point at the tip and are broadly attached at the base. The upper and lower surfaces are sparsely to moderately covered with spreading hairs and are dotted with scattered, stalkless or impressed glands. The margins are untoothed or may have a few teeth. The axis of the leaf is oriented north and south so that the blade faces east or west, thus avoiding the hot midday sun. Basal leaves are present at flowering time.

Stem leaves are alternate, short-stalked or stalkless, and otherwise similar to basal leaves. They become progressively smaller as they ascend the stem. Upper stem leaves 1½ to 6 long, short-stalked, and once pinnatifid.

The inflorescence is an elongated, usually branched cluster (panicle) of 6 to 30 flower heads at the end of the stem. The flower heads are short-stalked or nearly stalkless.

The flower heads are 2½ to 4 in diameter. The whorl of modified leaves (bracts) at the base of the flower head (involucre) is bell-shaped to hemispheric and to 13 16 in diameter. It is composed of 25 to 45 bracts (phyllaries) in 2 or 3 overlapping series. The phyllaries are egg-shaped, sharply pointed at the tip, ¾ to 19 16 long, and often spreading or bent backward at the tip. They are sparsely to densely hairy and are usually also dotted with glands.

There are 27 to 38 ray florets and 100 to 275 disk florets. The ray florets are yellow, ¾ to 2 long, and fertile. The disk florets are yellow and infertile.

The fruit is a dry, one-seeded seed capsule (cypsela). The cypsela is black to brown, egg-shaped, flattened, to 11 16 long, and ¼ to ½ wide. It is broadly winged and has a deep notch at the tip. There is no tuft of hairs attached to the end.




36 to 80


Flower Color


Yellow ray florets, yellow disk florets


Similar Species




Dry to moderate moisture. Prairies, railroads, disturbed areas. Full sun.




June to September


Pests and Diseases






Distribution Map



2, 3, 4, 5, 7, 28, 29, 30.









  Kingdom Plantae (green algae and land plants)  
  Subkingdom Viridiplantae (green plants)  
  Infrakingdom Streptophyta (land plants and green algae)  
  Superdivision Embryophyta (land plants)  
  Division Tracheophyta (vascular plants)  
  Subdivision Spermatophytina (seed plants)  
  Class Magnoliopsida (flowering plants)  
  Superorder Asteranae  


Asterales (sunflowers, bellflowers, fanflowers, and allies)  


Asteraceae (sunflowers, daisies, asters, and allies)  
  Subfamily Asteroideae  
  Supertribe Helianthodae  
  Tribe Heliantheae (sunflowers and allies)  
  Subtribe Engelmanniinae  
  Genus Silphium (rosinweeds)  

Subordinate Taxa


USDA PLANTS recognizes two varieties of Silphium laciniatum. Of these, only the nominate variety, var. laciniatum, occurs in Minnesota. Most other sources do not recognize any varieties.






Common Names




compass plant


tall speedwell










Twice pinnatifid. Cut deeply into lobes with each lobe also cut into deep lobes.



Modified leaf at the base of a flower stalk, flower cluster, or inflorescence.



A dry, one-chambered, single-seeded fruit, formed from a single carpel, with the seed attached to the membranous outer layer (wall) only by the seed stalk; the wall, formed from the wall of the inferior ovary and also from other tissues derived from the receptacle or hypanthium, does not split open at maturity, but relies on decay or predation to release the contents.



A whorl of bracts beneath or surrounding a flower or flower cluster.



A pyramidal inflorescence with a main stem and branches. Flowers on the lower, longer branches mature earlier than those on the shorter, upper ones.



An individual bract within the involucre of a plant in the Asteraceae family.



Deeply cut, more than half way to the midrib but not to the midrib, into lobes that are spaced out along the midrib; the lobes do not form separate leaflets.



A thin, flat, membranous, usually transparent appendage on the margin of a structure.

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    compass plant   compass plant  
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Flower Head

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Leaves in Early Spring

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  Silphium laciniatum COMPASS PLANT
Frank Mayfield
  Silphium laciniatum COMPASS PLANT  



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Other Videos
  Rare plant find prompts county to help

Published on Jun 19, 2012

Walter Stewart rushed to check it out and discovered a "sunflower-looking" plant referred to as "silphium laciniatum" or compass plant, first time it has ever been seen in Hays County.

  OEC Tallgrass Prairie Tour - July 19 - compass plant
Ohio Environmental Council

Uploaded on Jul 20, 2008

Guy Denny tells about the history and characteristics of the compass plant.






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