Silphium laciniatum L.
Source: USDA Plants_111306
Family: Asteraceae
compass plant,  more...
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John Hilty  
Plants scapiform, (40-)100-300 cm; taprooted. Stems terete, hirsute, hispid, or scabrous. Leaves: basal persistent, petiolate or sessile; cauline petiolate or sessile; blades lanceolate, linear, ovate, or rhombic, 4-60 × 1-30 cm, usually (proximal) 1-2-pinnately lobed, bases attenuate to truncate, ultimate margins unevenly toothed or entire, apices acute, faces hirsute, hispid, or scabrous. Phyllaries 25-45 in 2-3 series, outer reflexed or appressed, apices acuminate to caudate, abaxial faces hispid to scabrous, ± stipitate-glandular. Ray florets 27-38; corollas yellow. Disc florets 100-275; corollas yellow. Cypselae 10-18 × 6-12 mm; pappi 1-3 mm. 2n = 14. Flowering summer-early fall. Prairies, open, disturbed sites; 50-600 m; Ont.; Ala., Ark., Ill., Ind., Iowa, Kans., Ky., La., Mich., Minn., Miss., Mo., Nebr., N.Mex., N.Y., Ohio, Okla., Pa., S.Dak., Tenn., Tex., Wis.
Coarse, taprooted, rough-hairy, 1-3 m; lvs alternate, deeply pinnatifid or bipinnatifid, the lower very large, to 5 dm, progressively reduced upwards, the uppermost entire and well under 1 dm; heads in a narrow, sometimes racemiform infl, large, the disk 2-3 cm wide; invol 2-4 cm, exceeding the disk, its bracts ovate, acuminate, squarrose, not much imbricate; rays (13-)17-25(-34), 2-5 cm; 2n=14. Prairies; O. to Minn. and S.D., s. to Ala. and Tex.; locally intr. e. along railroads to N.Y. July-Sept. The basal lvs tend to align themselves in a north-south direction.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

©The New York Botanical Garden. All rights reserved. Used by permission.
From Flora of Indiana (1940) by Charles C. Deam
This species is a true prairie plant and in its distribution in Indiana it was restricted to the prairie areas. All of our prairie areas are under cultivation and it is found now only in moist prairie habitats along railroads and roadsides. The published records extend its range somewhat beyond that shown on the map. Beyond the area indicated by the map, it has been reported from the area of Delaware, Jay, Randolph, and Wayne Counties, and from Elkhart, Knox, and Noble Counties.
Silphium laciniatum image
Frank Mayfield  
Silphium laciniatum image
Peter Gorman  
Silphium laciniatum image
John Hilty  
Silphium laciniatum image
Peter Gorman  
Silphium laciniatum image
Peter Gorman  
Silphium laciniatum image
John Hilty  
Silphium laciniatum image
Peter Gorman  
Silphium laciniatum image
Peter Gorman  
Silphium laciniatum image
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