SENEGA 387 



POLYGALACEJE, OR MILKWORT FAMILY 



A family of about 750 species, mostly herbs, except in the tropics 

 where they may become shrubs and trees. The leaves are usually, 

 alternate and exstipulate, the flowers are perfect and irregular, and 

 the fruit is usually a capsule enclosing caruncled seeds. Among the 

 histological features of this family the following may be mentioned : 

 Small isolated groups of bast fibers occur in the pericycle of some of 

 the species of Polygala. Only the transverse walls of the tracheae are 

 marked by simple pores. The wood fibers possess bordered pores, 

 and the medullary rays are very narrow. The cells of the pith are 

 sometimes lignified. In the leaves there are several important char- 

 acteristics: (1) sclerotic cells are occasionally found in the loose 

 mesophyll and palisade layer; (2) in Polygala there is a strong ten- 

 dency for the epidermal cells to become papillose, thus resembling 

 the leaves of Erythroxylon ; and (3) terminal tracheids occur in the 

 veins of Polygala. Calcium oxalate is secreted in the form of solitary 

 crystals or rosette aggregates. Non-glandular hairs are mostly 

 unicellular, occasionally uniseriate. Glandular hairs are wanting. 

 In certain species of Polygala there are spheroidal aggregates of a 

 crystalline nature and Solereder suggests that they may have been 

 described by Chodat as lysigenous secretion cavities or oil cells in 

 certain South American species of Polygala. 



SENEGA. Senega Root. The dried root of Polygala Senega 

 (Fam. Polygalaceae) , a perennial herb found in Canada and the 

 eastern United States as far south as North Carolina and as far west 

 as Alberta, Minnesota and Missouri. There are two representative 

 commercial varieties the northern, collected in Manitoba and in 

 the State of Minnesota; the southern, from Virginia to Texas. 



Description. Southern Senega. Nearly entire, with broken and 

 detached rootlets, crowned with numerous buds and short stem-rem- 

 nants, slenderly conical, more or less tortuous, somewhat branched, 

 3 to 8 cm. in length, 2 to 6 mm. in thickness; externally dark yellow, 

 the crown being rose-tinted, longitudinally wrinkled, slightly annu- 

 late, marked with circular scars of detached rootlets and in some 

 cases by a keel, which is more prominent at the upper portion of the 

 dried roots; side opposite keel more or less flattened; fracture short 

 when dry, tough when damp; transverse section (Fig. 16.9) elliptical 

 or triangular, showing a characteristic excentral development of 

 lemon-yellow wood, which varies in outline from elliptical or ovate 

 to irregularly fan-shaped, and is surrounded by an unevenly devel- 

 oped dark yellow cortex, being thickest outside the broadest strands 



