PLANT TISSUES 
73 
Hyoscyamus, Belladonna and Digitalis leaves; hooked, as on stems 
of Phaseolus multi florus or Hops; barbed, as on the stems of Loasa 
species; or tufted, as found on the leaves of Marrubium vulgare. 
They may be simple as in Cotton, etc., or branched as in Hyoscyamus 
muticus. 
The glandular hairs comprise those whose terminal cell or cells are 
modified into a more or less globular gland for gummy, resinous or 
Fig. 23. — Lower epidermis of Comptonia asplenifolia leaf (surface view) 
showing stomata (s) scattered amongst epidermal cells. To the left is to be 
noted the globular head of a glandular hair. (Photomicrograph). 
oily deposits. They are generally composed of a stalk and a head 
region although rarely the stalk may be absent. The stalk may be 
unicellular, bicellular or uniseriate (consisting of a series of super- 
imposed cells). The head varies from a one- to many-celled struc- 
ture. The drug Lupulin consists of the glandular hairs separated 
from the strobiles of HumuJus lupulus. 
Scales are flat outgrowths of the epidermis composed of one or 
several layers of cells. They occur attached to the stipes of Aspid- 
