THE EPIDERMIS AND PERIDERM 69 



of the stigma. The style papillae are always smaller, and they 

 are of a different form. 



UNICELLULAR NON-GLANDULAR HAIRS 



True plant hairs are tubular outgrowths of the epidermal 

 cell, the length of these outgrowths being several times the 

 width of the hair. 



The unicellular hairs are common to many plants. The two 

 groups of non-glandular unicellular hairs are, first, the solitary; 

 and secondly, the clustered hairs. 



Solitary unicellular hairs occur on the leaves of chestnut, 

 yerba santa, lobelia, cannabis indica, the fruit of anise, and 

 the stem of allspice, senna, and cowage. 



Chestnut hairs (Plate 7, Fig. i) have smooth yellowish-colored 

 walls, and the cell cavity contains reddish-brown tannin. These 

 hairs occur solitary or clustered; the clustered hairs normally 

 occur on the leaf, but in powdering the drug, individual hairs of 

 the cluster become separated or solitary. 



Yerba santa hairs (Plate 7, Fig. 4) are twisted, the lumen or 

 cell cavity is very small, and the walls, which are very thick, 

 are grayish- white. 



Lobelia hairs (Plate 7, Fig. 5) are very large. The walls 

 are grayish-white, and the outer surface extends in the form 

 of small elevations which make the hair very rough. The hair 

 tapers gradually to a solid point. 



Cannabis indica hairs (Plate 7, Fig. 6) are curved. The 

 apex tapers to a point and the base is broad, and it frequently 

 contains deposits of calcium carbonate. The walls are grayish- 

 white in appearance, and rough. The roughness increases 

 toward the apex. 



The hairs of anise (Plate 7, Fig. 7) are mostly curved; the 

 walls are thick, yellowish- white, and the outer surface is rough; 

 this is due to the numerous slight centrifugal projections of the 

 outer wall. 



Allspice stem hairs (Plate 7, Fig. 2) have smooth walls. 

 The cell cavity is reddish-brown. The hair is curved. 



The hair of senna (Plate 7, Fig. 10) is light greenish-yellow 

 with rough papillose walls. The hair is usually curved and 

 tapering, and it does not have any characteristic cell contents. 



