390 IMPERAT01UA. [CLASS V. ORBER II. 



GENUS LXXVI. IMPE V RATORIA. LINN. Master-wort. 



GEN. CHAR. Calyx margin obsolete, ( the rest as in Peucedanum ) . 

 Name from impero, to overcome ; so named because its leaves 

 extend over smaller plants and smother them. 



1. /. Os truth 'rum, Linn. (Fig. 456.) Great Masterwort. Leaves 

 bi-ternate; leaflets broadly ovate, cut and serrated, unequal at tbe 

 base; sheath of the footstalks very large; general involucre wanting. 



English Botany, t. 1380. English Flora, vol. ii. p. 78. Peucedanum 

 Ostruthium, Koch. Hooker, British Flora, vol. i. p. 135. Lindley, 

 Synopsis, p. 116. 



Root tuberous, with long spreading fibres, fleshy, acrid and aromatic. 

 Stem erect, from one to two feet high, round, smooth, finely striated, 

 leafy, scarcely branched above. Leaves on long footstalks, with large 

 dilated striated membranous sheaths, mostly purple on the margin, 

 ternate, with large broadly ovate lanceolate leaflets, unequal at the 

 base, the lower edge shortest, irregularly cut and serrated, the lateral 

 ones with a large lobe on the lower side, sometimes of three lobes, as 

 is always the terminal leaflet, somewhat paler beneath, with prominent 

 ribs and netted slender veins, the upper leaves much smaller than the 

 lower. Umbels terminal, and sometimes lateral, large, the general of 

 numerous long unequal striated rays, and the partial of numerous 

 unequal slender ones. General involucre wanting, partial of a few 

 linear segments. Flowers numerous, white, crowded, nearly equal. 

 Calyx an obsolete margin. Petals inversely heart-shaped, with a small 

 indexed point. Stamens on long slender^j/amewte, with small roundish 

 ovate anthers. Styles short, spreading, with obtuse stigmas. Disk 

 yellow, fleshy, somewhat conical. Fruit oblong, flat, with a broad 

 dilated flat margin, notched at the base and apex. Carpels with five 

 slender filiform equi-distant ridges, three at the back, the two lateral 

 ones scarcely distinguishable, close to the margin. Albumen flat. 



Habitat. Moist pastures in various parts of Scotland, but a doubt- 

 ful native. 



Perennial ; flowering in June. 



This plant was formerly considered an infallible remedy for almost 

 all wounds and disorders of the body, hence some say it derived the 

 common name of Master-wort. Its root is acrid, bitter, with an 

 aromatic flavour, and is recommended as a masticatory to relieve tooth- 

 ache; but although so much extolled formerly as to obtain for it the 

 distinguished appellation of divinum remedium, it is now almost out 

 of use, being superseded by other more powerful medicines. 



