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HISTOLOGY OF MEDICINAL PLANTS 
Cowage hairs (Plate 7, Fig. 3) are lance-shaped, and they 
terminate in a sharp point. The outer wall contains numerous 
recurved teeth-like projections. The cell cavity is filled with 
a reddish-brown contents which are somewhat fissured. 
Clustered unicellular hairs occur on the leaves of chestnut, 
witch-hazel, althea, European oak, etc. In European oak (Plate 
8, Figs. 1 and 2) clusters of two and three hairs occur. The 
walls are yellowish-white, smooth, and the tip of the hair is solid. 
In kamala (Plate 8, Fig. 3) clusters of seven or more hairs 
occur; the walls are yellowish, and the cell cavity is reddish- 
brown. In witch-hazel leaf (Plate 8, Fig. 4) clusters of a variable 
number of hairs occur. The hairs, which are of various lengths, 
have yellowish-white, thick, smooth walls, and reddish cell 
contents. 
In althea leaf (Plate 8, Fig. 5) the hairs are nearly straight 
and the walls are smooth. The basal portions of the hair are 
strongly pitted. 
Branched solitary unicellular hairs occur on the leaves of 
hesperis matronalis (Plate 7, Fig. 8), and on galphimia glauca 
(Plate 7, Fig. 9). 
The hair of hesperis matronalis has smooth walls, and the 
two branches grow out nearly parallel to the leaf surface. 
_ The hair of galphimia glauca has rough walls, and the two 
branches grow upward in a bifurcating manner. 
MULTICELLULAR HAIRS 
Multicellular hairs are divided into the uniseriate and the 
multiseriate hairs. Both of these groups are divided into the 
branched and the non-branched hairs, as follows: 
1. Uniseriate. | 
(A) Non-branched. 
(B) Branched. 
2. Multiseriate. 
(A) Non-branched. 
(B) Branched. 
Multicellular uniseriate non-branched hairs occur on the 
leaves of digitalis, Western and Eastern skullcap, peppermint, 
thyme, yarrow, arnica flowers, and sumac fruit. 
Digitalis hairs (Plate 9, Fig. 1) are made up of a varying 
