ya ge PHARMACEUTICAL BOTANY 
SuccuLENT.—In a completely centric leaf of the succulent 
kind, like that of Sedum murale the difference between the upper 
and lower surface is lost. Stomata are found scattered over the 
entire epidermis. The bundles are arranged in a circle, the mid- 
rib being in the center. A great deal of mucilage is found stored 
in the central cells. 
XEROPHYTIC.—In a typical Xerophytic Centric leaf, like that 
of the Pine (see Figs. 168 and 169) or Sansevierta cylindrica, the 
Fic. 168.—Transverse section of the xerophytic-centric leaf of the Austrian 
Pine (Pinus nigra), magnified. ep, epidermis; s, deeply sunken stomata; Af, hypo- 
dermal fibers; 7p, infolded parenchyma; 0.r., schizogenous oil reservoirs; f, fibers; 
n, bundle sheath (endodermis) surrounding the stele in which will be noted two 
vascular bundles with xylem (x) directed toward the flat face of the leaf; ph, phloem 
of vascular bundle; mr, medullary ray: scl, sclerenchymatous cells; p, small celled 
parenchyma of pith. 
epidermis shows a thick cuticle; the stomata are sunken in 
cavities of the epidermis; the epidermis and leaf tissue are 
strengthened by scleroid bands in the outer portion of the 
centric mesophyll. 
D. BrractaL.—Leaves with laminz which stand edge on in 
relation to the sun’s rays. The best illustrations are seen among 
dicotyledons, such as Eucalyptus, Callistemnon, and other genera of 
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