§0 BOTANY FOR BEGINNERS. jCh. X. 
238. The “ fall of the leaf” may be referred to two causes; 
the death of the leaf, and the vital action of the parts to which 
tt is attached. If a whole tree is killed by lightning, or any 
sudden cause, the leaves will adhere to the dead branches, be- 
cause the latter have not the energy to cast them off. 
239. The richness and variety of colouring exhibited about 
the end of autumn, by American groves and forests, is splendid 
beyond the power of the painter to imitate. Yellow, red, and 
brown, are the most common colours of the dying leaf; but 
these colours vary from the brightest scarlet, and the deepest 
crimson, to different shades of yellow, from the deep orange to 
-he pale straw colour. 
Appendages to Plants. 
240. Plants have a set of organs called by the general name 
of appendages. These we shall now describe. 
Fig. 38. 
241. Stipules are 
membranous or leafy 
scales, usually in 
pairs, at, or near the 
base of the leaf or 
petiole. They are 
various in their forms 
and situations, are 
found in most plants, 
but are sometimes 
wanting. In the garden violet, Viola tricolor, (Fig. 38, a, a,)} 
the stipules are of that form called lyrate pinnatifid, while the 
true leaf (0) is oblongandcrenate. The most natural situation 
of the stipules is in pairs, one on each side of the base of the 
footstalk, 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. 
242. Prickles, arise from the bark; they are sometimes 
straight, sometimes hooked, and sometimes 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 
238. 'T'o what may the fall of the leaf be referred ? 
239. What is said of the appearance of American forests in the Au 
tumn.? 
240, What organs have plants besides those already named? 
241. Describe stipuies. 
242. Describe prickles. 
