io8 
PHARMACEUTICAL BOTANY 
The epidermis of leaves, stems, fruits, and seeds of many plants 
frequently give rise to outgrowths in the form of papillae, hairs 
and scales. Epidermal papillce ^re short protuberances of epidermal 
cells. They may be seen to advantage on the upper epidermis of the 
Pig. 47. 
Fig. 46. 
Pig. 46.—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; 
5 and 6, epidermal outgrowths in the form of scales and hairs. (1, 2, 6 after 
Stevens, 3 after Slrasburger, 4 after Sachs, and 5 after de Bary .) 
Pig. 47.—Different forms of epidermal outgrowths. 1, Hooked hair from 
Phaseokis 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 Haberlandt.) 
ligulate corolla of various species of Chrysanthemum , on the lower 
epidermis of the foliage leaves of species of Erythroxylon and upon the 
upper epidermis of the petals of the Pansy (Viola tricolor). Epi¬ 
dermal hairs or trichomes are more elongated outgrowths of one 
or more epidermal cells. They may be unicellular (Cotton) or 
