66 
APPENDAaES TO PLANTS. 
Fig. 63. 
organs are somewhat donbtful ; but we should not infer be- 
cause the design for which they were formed is in some meas- 
ure concealed from us, that they were made for no purpose oi 
exist by mere accident ; it would be impious for us to imagine 
that ail the works of God which we cannot comprehend are 
useless. 
There are various vegetable organs which have been called 
by the general name of appendages ; they are the following : 
stipules^ prickles^ thorns^ glands^ stings^ scales^ tendrils^ pubes- 
cence^ and bracts. 
a. Stipules are membraneous or leafy 
scales, usually in pairs, at, or near the base 
of the leaf or petiole. They are subject to 
the same laws of venation, and perform the 
same offices as leaves. They sometimes 
develop buds in their axils. "When they 
^row from the stem they are the rudiments of leaves ; when 
irom the base of the petiole, they are the undeveloped leaflets 
of a pinnate leaf. "We see therefore that stipules are modified 
or transformed leaves. The stipules furnish characters used in 
botanical distinctions. They are various in their forms and 
situations, are found in most plants, though sometimes wanting. 
In the garden violet, viola tricolor (Fig. 63, a a), the stipules 
are lyrate-pinnatifid^ while the true leaf (b) is oblong and 
crenate. The most natural situation of the stipules is in pairs, 
one on each side of the base of the foot-stalk, as in the sweet-pea ; 
some stipules fall off almost as soon as the leaves are expanded, 
but in general they remain as long as the 
leaves. Fig. 64 shows a portion of a branch 
of a species of willow ; I represents part of 
a single petiolate leaf; s s^ stipules ; bud 
in the axil of the leaf. 
h. Prickles arise from the bark ; they con- 
sist of hardened cellular tissue, and are re- 
moved with the cuticle ; they have not like 
the thorn connection with the wood, nor do they disappear by 
cultivation; they are straight, hooked, or forked. They are 
usually found upon the stem, as in the rose ; but in some cases 
they cover the petiole, as in the raspberry ; in others, they are 
found upon the leaf or the calyx, and in some instances, upon 
the berry, as in the gooseberry. 
G. Tho7''ns^ or spines, are distinguished from prickles by 
growing from the woody part of the plant. Although the bark 
may be separated from a thorn-bush, the thorn will still remain 
projecting from the wood. 
64. 
a. St.ioiiles — h. Prickles — c. Tiiorna. 
