4S6 BOTANY AND PHARMACOGNOSY. 



Inner Structure. — See Fig. loi, E. 



Constituents. — An alkaloid pyrethrine, which occurs in col- 

 orless, acicular crystals, has an intense pungent taste, and which 

 is decomposed by alkalies into piperidine (a pungent principle 

 occurring in black pepper) and pyrethric acid, a principle resem- 

 bling piperic acid. Pyrethrum also contains a brown acrid resin, 

 two other acrid resins, a volatile oil and about 50 per cent.' of inulin. 



Allied Pl.\nts. — German pellitory, the root of Anacyclus 

 oMcinarum, is smaller ; the bark contains but one row of secretion 

 reservoirs, which are wanting in the medullary rays ; and the roots 

 contain tannin in addition to the constituents found in Pyrethrum. 



SENEGA.— SENEGA. ROOT.— The dried root of Polygala 

 Senega (Fam. Polygalacese), a perennial herb (p. 313) found in 

 Canada and the Eastern United States as far south as North Caro- 

 lina and as far west as Minnesota and Missouri (Fig. 197). 

 There are two representative commercial varieties — the northern, 

 collected in Manitoba and in the State of Minnesota; the south- 

 ern, from Virginia to Texas. 



Description. — Southern Senega. — Nearly entire, with 

 broken and detached rootlets, crowned with numerous buds and 

 short stern-remnants, slenderly conical, more or less tortuous, 

 somewhat branched, 3 to 8 cm. long, 2 to 6 mm. thick ; externally 

 dark yellow, the crown being rose-tinted, longitudinally wrinkled, 

 slightly annulate, marked with circular scars of detached rootlets ■ 

 and in some cases by a keel which is more prominent near the 

 crown and in perfectly dry roots ; side opposite keel more or less 

 flattened; cross-section elliptical or triangular; fracture short 

 when dry, tough when damp ; internally, wood lemon-yellow, 2 to 

 5 mm. in diameter, usually excentral, bark dark yellow, much 

 thickened on one side, forming the keel on drying; odor slight, 

 penetrating; taste sweetish and acrid (Fig. 197a). 



Manitoba Senega is 8 to 15 cm. long, 6 to 12 mm. thick, 

 externally dark brown and somewhat purplish near the crown. 



Constituents. — The principal constituents are about 5 or 6 

 per cent, of two glucosides : senegin, which resembles saponin, 

 and polygalic acid, which is sternuatory. The root also contains 

 0.12 per cent, of a volatile oil which is chiefly methyl salicylate; 

 resin, pectin, sugar and considerable proteids. 



