GENERAL DESCRIPTION AND PARTS OF THE LEAF. 141 
axillary to the leaf; or, if from the stem above, or below the 
axil, it is extra-axillary ; or, as more generally described when 
above, supra-axillary ; if below, infra-axillary. 
Duration and Fall of the Leaf.—The leaf varies as regards 
its duration, and receives different names accordingly. Thus, 
when it falls off soon after its appearance, it is said to be 
fugacious or caducous; if it lasts throughout the season in 
which it is developed, it is deciduous or annual; or if beyond 
a single season, or until new leaves are developed, so that the 
plant is never without leaves, it is persistent, everyreen, or 
perennial. 
When a leaf separates from the stem or branch, it either does 
so by decaying upon it, when it is said to be non-articulated ; or by 
an articulation, in which case it is articulated. The remains of a 
non-articulated leaf, as they decay upon the stem, or branch, are 
Fic. 273. 
Rie. 274. 
Fig. 273. Leaf and piece of the stem of Polygonum Hydropiper. 1. Lamina 
or blade. p. Petiole. d. Sheath.—Fig. 274, Leaf and portion of a 
branch of Saliz aurita. 7. Branch. 6. Bud, J. Lamina with the upper 
portion removed, and attached by a petiole, p,to the stem. s,s. Caulinary 
stipules. 
sometimes called reliquix or induvie, and the stem or branch is 
said to be induviate. Whena leaf separates by an articulation, it 
leaves a scar or cicatrix (fig. 207, b, b). 
Parts of the Leaf.—The leaf in the highest state of develop- 
ment consists of three distinct parts ; namely, of an expanded 
portion, which is usually more or less flattened (jigs. 273 and 
274, 1), called the lamina, or blade; of a narrower portion, 
by which the lamina is connected with the stem, termed the 
petiole or leaf-stalk (p); and of a third or stipular portion, 
which is situated at the base of the petiole, and which either 
exists in the form of a sheath (fig. 275, d), encircling the stem, 
or as two little leaf-like appendages on each side, which are 
called stipules (fig. 274, s, s). 
These three portions are by no means always present, though 
