150 PHARMACEUTICAL BOTANY 
NECTARIES 
Nectaries are nectar-secreting tissues, consisting either of 
groups of modified cells or of specialized glands, tubes or cavities 
found on insect-pollinated plants. ‘The nectar secreting tissue 
occurs usually on parts of the flower but may occur on petioles, 
stipules, bracts or other structures. Nectar is a sugary secretion 
which is exuded through the outer walls of the cells of the 
Fic. 88.—Resin duct (secretion reservoir) in leaf of Pinus sylvestris, in cross- 
section at A, and in longitudinal section at B; h, cavity surrounded by the secret- 
ing cells; f, f, sclerenchyma fibers surrounding and protecting the duct. (Stevens 
after Haberlandt.) 
nectary. When the nectar secreting tissue is superficial the 
modified epidermal cells are often palisade-like or papillose in 
form, but may consist of dense groups of club-shaped hairs. 
In numerous plants as more elaborate structures such as sunken 
pouches, as in the buttercups, or elevated glandular structures 
lined with nectar secreting structures, as on the petioles of 
Viburnum Opulus, etc. 
CLASSIFICATION OF ‘TIssuES ACCORDING TO FUNCTION.— 
According to their particular function, tissues may be classified 
as follows: 
