FAMILY: Compositae (Asteraceae)
HABIT: Herbaceous perennial, 1.0-3.5 m.; flowering
late July-August; fruiting September, October.
SPECIES: Flowering plants are very distinctive
and conspicuous. Vegetative specimens
can be confused with non-flowering plants of prairie-dock (Silphium
terebinthinaceum), especially with cut-leaved variants of the latter. In other states, hybrids between these two species
have been reported.
RANGE: OH, MN, and ND, s. to OK and TX.
RANGE: A single population is extant in
Lawrence County. Reported in 1966 from
a site in Erie County that subsequently has been disturbed, the species no
longer can be found there. There are
pre-1960 records from Franklin and Summit counties.
STATUS: 1980 to present: Endangered.
HABITAT: In full sun on well-drained, clay or
calcareous substrates: pastures, dry prairies, railroad embankments. The Ohio population occurs on a steep,
grazed slope subject to landslips.
HAZARDS: Overgrowth by woody species; over-grazing.
POTENTIAL: Probably very good; the
species grows well in cultivation and is tolerant of moderate disturbance; the
deep taproot resists seasons of drought.
GUIDELINES: Identification should be
based upon flowering material only; many other composites are popularly called
“compass-plant,” such as wild lettuce (Lactuca sp.).
COMMENTS: This species when in bloom is exceedingly
conspicuous. Its distribution in Ohio
probably is accurately known. Fisher
(1966) suggests, though, that the prairie-dock (Silphium terebinthinaceum)
in Marion County shows evidence of introgression from S. laciniatum. Though no compass-plant has ever been
reported from Marion County, it may have been found there at one time. Further research may help elucidate the
Some authors split this species into
two varieties, though most taxonomists do not accept this concept. Under such a treatment, Ohio plants are the
T.M. and W.A. Wistendahl. 1983. Demography and persistence of Silphium
laciniatum at the O.E. Anderson Compass Plant Prairie. p. 30-32. In: Brewer, R. (ed.) Proceedings of the eighth North American
Prairie Conference. Western Michigan
Univ., Kalamazoo, MI. 176 p.
A. 1980. Vascular flora of the southeastern United States. Vol. I.
Asteraceae. Univ. of North Carolina Press, Chapel Hill, NC. xv + 261p.
A.W. 1981. Compass-plant (Silphium lsciniatum) in Ohio: its historic
and present-day distribution. (abs.) p. 262.
In: Stuckey, R.L. and K.J. Reese., eds. The Prairie Peninsula –
in the “shadow” of Transeau. Proc. Sixth N.A. Prairie Conference. Ohio Biol. Surv. Biol. Notes No. 15. 278 p.
T.R. 1966. The genus Silphium in Ohio. Ohio J. Sci. 66: 259-263.
1988. The Dicotyledoneae of Ohio. Part 3. Asteraceae. Ohio State Univ. Press,
Columbus. 280 pp.
Division of Natural Areas and Preserves
Ohio Department of Natural Resources
Created: 2/1984 Allison W. Cusick
Database Code: SPNX.E13