WOODY PLANTS IN WINTER 3 



squarish plates and has the general appearance of alligator lea- 

 ther (Fig. 5). In cherries and birches the bark peels horizontally 

 into thin sheets (Fig. 3). Broad exfoliating plates characterize 

 certain hickories. Deeply furrowed bark is found on many trees, 

 as chestnut oak (Fig. 2). Lumbermen often rely almost wholly 

 upon bark characteristics in the identification of timber species, 

 but the features are often difficult to describe so they can be 

 recognized. Experience is most important in this type of identi- 

 fication. 



TWIGS 



The terminal portion of a branch of a woody plant may be 

 referred to as a branchlet or twig (Figs. 6, 7). In this work these 

 terms are used to designate, specifically, the growth of the cur- 

 rent year and, to a lesser extent, that of the last preceding year. 

 Twigs bear prominent distinguishing features such as buds, leaf- 

 scars, stipule-scars, and pith, while their color, taste, and odor 

 may also be distinctive. Various other features, such as corky 

 ridges, thorns, and pubescence characterize certain species. 



Color and hairiness of twigs are important winter characters, 

 although they might more properly be regarded as physiological 

 effects rather than physical features. 



During the winter the color tends to become darker on the 

 side most exposed to the sun (the upper, or southern sides). Twigs 

 which are green in summer may become reddish in winter through 

 the formation of anthocyanins, favored by cold weather. There- 

 after the color deepens each year, for two or three or even four 

 years. Hairs also change somewhat in color, as well as in abun- 

 dance as the winter season progresses. Twigs become less and 

 less hairy in the second and later years, under ordinary condi- 

 tions. Of course some are glabrous from the beginning. 



Buds. A bud, literally, is a growing point, the early unde- 

 veloped stage of a leafy shoot or a flower. In winter, of course, 

 the growing points are dormant, and are usually covered, for pro- 

 tection, by bud scales , which are really modified leaves. 



Buds are of two types, the terminal buds at the tips of the 

 stem and its branches, and the lateral buds, along the sides of the 

 branchlets (Fig. 6). In some species a true terminal bud is not 

 formed and growth continues throughout the season until stopped 

 by unfavorable weather. When this has happened, the young ten- 

 der tip of the shoot dies back and is finally self-pruned at the high- 

 est mature lateral bud formed. This bud then appears to be ter- 

 minal and is referred to as a pseudoterminal bud. Usually it con- 

 tinues the growth of the shoot in the next season, in much the same 

 manner as an actual terminal bud would have done. A pseudoter- 



