242 PHARMACEUTICAL BOTANY 
Villose, covered with long and shaggy hairs. Example: 
Forget-me-not. 
Sericious, when covered with hairs which give a silky appear- 
ance. Example: Silverleaf. 
Hispid, when covered with short, stiff hairs. Example: 
Borage. 
Strigose, when covered with appressed, stiff and sharp hairs. 
Tomentose, densely pubescent and felt-like, as the Mullein leaf. 
Spinose, beset with spines, as in the Thistle. 
Rugose, when roughened with closely set wrinkles. Example: 
Sage. 
Verrucose, covered with protuberances or warts, as the calyx of 
Chenopodium. 
Tuberculate, when covered with minute wart-like projections. 
Bullate, when blister-like projections appear between the 
veins. 
Duration oF Leaves.—Leaves vary as to their period of 
duration. They are: Persistent, or evergreen, if they remain green 
on the tree for a year or more. 
Deciduous, if unfolding in spring and falling in autumn. 
Caducous, or fugacious, if falling early in the season. 
Parts oF TypicaL Lear.—The parts of a typical leaf are 
petiole or leaf stalk, /amina or blade, and stipules. 
Tue PETIOLE 
The PretioLE iv MonocotyLepons is usually a broadened, 
sheathing basal structure which connects the lamina to the stem. 
In the Grasses and Bananas it forms a long tubular sheath which 
surrounds the stem. At the point of union of the sheathing 
petiole and the lamina of a grass is a membranous or leathery 
ring or flap called the Licute. The ligule is not a part of the 
petiole but is a formation due to the upgrowth and union of a pair 
of stipules. Into the Grass petiole a set of closed collateral 
vascular bundles of the stem extend, these showing xylem upper- 
most and phloembeneath. Inthe Palms, Aroids, Yams, Bananas, 
the petiole in part or throughout may be much thickened, 
strengthened and developed as a semi-cylindric or cylindric 
structure frequently showing, as in Palms, generally, two sets of 
