Tas. 6534, 
SILPHIUM LACINIATUM. 
The Compass Plant of the Prairies. 
Nat. Ord. Composirm.—Tribe HELIANTHOIDER. 
Genus Sinpuium, Linn. ; (Benth. et Hook.f. Gen. Pl. vol. ii. p- 350.) 
SILPHIUM laciniatum ; erectum, 3-8 pedale, ubique hispido-setosum, caule simplici 
valido folioso, foliis petiolatis pinnatipartitis lobis magnis elongatis sub- 
distantibus linearibus v. lineari-oblongis acutis remote dentatis lobatis pinna- 
tifidisve petiolo amplexicauli, capitulis paucis subterminalibus subracemosis 
3-5 poll. diam., involucri bracteis late ovatis apicibus patentibus v. recurvis 
viridibus herbaceis, ligulis 20-30 horizontalibus anguste lineari-oblongis, 
2-nerviis, acheniis late alatis apice profunde emarginatis. 
8. laciniatum, Linn. Sp. Pl. n. 1301; DC. Prodr. vol. vi. p- 512; Linn. fil. Dec. 
p. 5, tab. 3; Jacq. fil. Eclag. i. tab. 90; A. Gray, Bot. N. U. States (ed. 5), 
9. 
p. 24 
S. spicatum, Poir, Suppl. vol. v. p. 157. 
This noble plant was introduced into Europe, in 1781, by 
M. Thouin, and flowered for the first time in the Botanic 
Garden of Upsala in Sweden. It has been in cultivation in 
Europe ever since, though its name and fame as the 
Compass Plant of the Prairies is of comparatively modern 
date, it having before that borne the popular names of 
Turpentine Plant and Rosin-weed, except amongst the 
hunters and settlers in the Western States. With regard 
to the history of its reputed properties as an indicator of 
the meridian by the position of its leaves, I am fortunate 
in having recourse to my friend Professor Asa Gray, now 
in England, who has most kindly furnished me with the 
following very interesting account of this matter :— 
**The first announcement of the tendency of the leaves 
of the Compass Plant to direct their edges to the north and 
south was made by General (then Lieutenant) Alvord, of 
the U.S. army, in the year 1842, and again in 1844, in 
communications to the American Association for the 
JANUARY Isr, 1881. 
