PY 'RETHRUM* * 
Linnean Class and Order. Syngene'sia f , Polyga'mia, 
SUPERFLUA %. 
Natural Order. Compo'sitas §, Adans. Tribe, Corymbi- 
FER/E ||, Juss. — Lindl. Syn. pp. 140 & 143.; Introd. to the Nat. 
Syst. pp. 197 & 199. — Loud. Hort. Brit. pp. 520 & 522. Synan- 
the're.e, tribe, Corymui'fer.e, Rich, by Macgilliv. pp. 454 & 
455. — Corymbi'fer.iE, Juss. Gen. PI. p. 177. — Sm. Gram, of 
Bot. p. 121. 
Gen. Char. Involucrum ( common calyx ) (fig. 1.) hemisphe- 
rical, imbricated. Scales oblong, nearly equal, bluntith, with 
membranaceous margins. Corolla compound, radiant ; florets of 
the disk (fig. 2.) perfect (having both stamens and a pistil), tubu- 
lar, with 5 equal spreading segments; those of the radius (fig. 3.) 
numerous, strap-shaped, spreading, with 3 terminal teeth. Ft la- 
ments 5, hair-like, short, in the tubular florets only. Anthers 
united into a cylindrical tube. Germen angular, abrupt. Style 
thread-shaped, not longer than the anthers. Stigmas spreading, 
blunt, somewhat notched. Seed-vessel none, the calyx remaining 
unchanged. Seed (fig. 4.) in all the florets oblong, angular, abrupt, 
furrowed, crowned with an elevated membranous border. Recep- 
tacle (fig. 6.) naked, convex. 
Distinguished from other genera, with strap-shaped marginal 
florets and a naked receptacle, in the same class and order, by 
the elevated membranous border which crowns the seed ; and the 
hemispherical, imbricated calyx, whose scales are rather acute and 
membranous at the edges. 
Three species British. 
PY'RETHRUM PARTHE'NIUM. Common Feverfew. 
Spec. Char. Leaves stalked, compound, flat, leaflets egg- 
shaped, cut, the uppermost confluent (running one into the other 
at the base). Flower-stalks corymbose. Stem upright. Rays 
shorter than the diameter of the disk. 
Engl. Bot. t. 1231.— Sm. FI. Brit. v. ii. p. 900. Eng. FI. v. iii. p. 451. — With. 
(7th ed.) v. iii. p. 951. — Hook. Brit. FI. p. 365. FI. Scot. p. 246. — Relh. FI. 
Cant. (3rd ed.) p. 349. — Grev. FI. Edin. p. 180. — FI. Devon, pp. 140 5c 160. — 
Fig. 1. Involucrum. — Fig. 2. Tubular floret of the Disk. — Fig. 3. Strap- 
shaped floret of the Ray. — Fig. 4. Seed. — Fig. 5. Receptacle, with the seed 
upon it. — Fig. 6. Receptacle, with the seed taken off. — Figs. 2 & 4 magnified. 
* From its resemblance to the Purethron , Gr. of Dioscorides, so called from 
pur , fire, on account of its acrid roots. Dr. Hooker, in Br. FI. 
t The 19th class in the Linnean System, comprehending all those plants with 
compound flowers, the stamens of which are united by their anthers into a tube. 
It is a very natural and extremely numerous class. 
I The second order of the Linnean class Svncene'si*, containing all those 
compound flowers in which the florets of the disk have, each of them, 5 sta- 
mens and a pistil, and the florets of the ray a pistil only, and all producing 
perfect seed. 
$ See Prendnthes muralis, t. 27. H See Achillea Ptdrmica, t. 36. 
