STRUCTURE OF LEAF-BUDS. 105 
covered with a resinous secretion, as in the Horsechestnut and 
several species of Poplars ; or with a dense coating of soft hairs 
or down, as in some Willows. Such scales, therefore, by inter- 
posing between the tender rudimentary leaves of the bud and 
the air a thick coating of matter which is a bad conductor of 
heat and insoluble in water, protect them from the influence 
of external circumstances, by which they would be otherwise 
injured, or even destroyed. Buds thus protected are sometimes 
termed scaly. In the buds of tropical regions, and those of 
herbaceous plants growing in temperate climates which are not 
thus exposed to the influence of a winter, such protective organs 
would be unnecessary, and are accordingly absent, and hence all 
Fic. 207. Fig. 208. Fic. 209. 
Fig. 207. A shoot one year old of the Horsechestnut, with terminal bud. 
a. Sear produced by the falling off of the bud-scales of the previous year, 
b, 6. Scars caused by the falling off of the petioles of the leaves of the 
present year, with buds, c, in their axils.——Fig. 208. Diagram to illus- 
trate the growth of the shoot from the bud. e¢, c, c. The nodes where the 
leaves are situated. d,d. The internodes developed between them,—— 
Fig. 209. Shoot of the Lilae (Syringa vulgaris), showing suppression of 
the terminal bud, and two lateral buds in its place ( false dichotomy). 
the leaves of these buds are nearly of the same character. Such 
buds are called naked. In a few instances we find even that 
the buds of perennial plants growing in cold climates, and 
which are exposed during the winter, are naked like those of 
tropical and herbaceous plants. Such is the case, for instance, 
with the Alder Buckthorn (Rhamnus Frangula), and those of 
some species of Vibwrnwm. 
These protective organs of the bud are commonly, as we have 
just mentioned, termed scales, but they have also received the 
name of teymenta. That such scales are really only modified 
leaves adapted for a special purpose, is proved not only by their 
position with regard to the true leaves, but also from the gradual 
transitional states, which may be frequently traced from them 
to the ordinary leaves of the bud. These scales have only a 
