74 
PHARMACEUTICAL BOTANY 
ium, Osmunda and other ferns where they are called “chaff scales.” 
They are also found on a number of higher plants. 
Plant hairs are adapted to many different purposes. They may 
absorb nourishment in the form of moisture and mineral matter 
Fig. 25. 
Fig. 24. 
Fig. 24. — 1, Epidermis of oak leaf; 2, epidermis of Iris leaf, both viewed from 
the surface; 3, group of cells from petal of Viola tricolor; 4, two epidermal cells 
in cross-section showing thickened outer wall differentiated into three layers, 
namely, an outer cuticle, cutinized layer (shaded), and an inner cellulose layer; 
S and 6, epidermal outgrowths in the form of scales and hairs. (1, 2, 6 after 
Stevens, 3 after Strasburger, 4 after Sachs, and 5 after de Bary.) 
Fig. 25. — Different forms of epidermal outgrowths. 1, Hooked hair from 
Phaseolus multiflorus; 2, climbing hair from stem of Humulus Lupulus; 3, rod- 
like wax coating from the stem of Saccharum officinarum; 4, climbing hair of 
Loasa hispida; 5, stinging hair of Urtica urens. {Fig- 3 after de Bary; the re- 
mainder from Haberlandl.) 
in solution, e.g., root hairs. Those which serve as a protection to the 
plant may be barbed and silicified, rendering them unfit for animal 
food, or, as in the nettle, charged with an irritating fluid, penetrating 
the skin when touched, injecting the poison into the wound. A dense 
covering of hairs also prevents the ravages of insects and the clogging 
