Trees and How to Know Them [ 347 



which includes the white oak proper, the bur, post, and Cali- 

 fornia white oak it helps to examine the leaves. They have 

 characteristically rounded lobes (segments) , though the chestnut 

 oak is a well-known exception with its long narrow leaves. Usually 

 they are light-colored on the underside. 



Another characteristic of these trees is the grayish or light- 

 brown bark which you may often notice breaking off in loose, 

 flaky scales. (This, again, is not true of the chestnut oak.) Acorns 

 of the white oaks mature in one year; you will never see acorns 

 of old and new crops on a tree at the same time. 



The Black Oaks: The black oak group, by contrast, has leaves 

 with angular lobes, ending in sharp points. Members of this 

 group, including the black, pin, red, scarlet, Spanish, and willow 

 oaks, require two years to mature their acorns; so you may observe 

 fully grown acorns started the previous year and the new crop 

 clinging to the branches at the same time. 



As for differentiating oak species, you will find such distinc> 

 tions as the pin oak's horizontal, slender branches that arch out 

 gracefully and on the lower part of the tree droop and spread out 

 into fine branchlets most unusual for an oak. The willow oak is 

 distinctive in that its slender leaves have no lobes. The black oak 

 has rough, dark bark growing in ridges; the bark of the scarlet 

 oak is even rougher. The red oak's acorns are large and set in 

 broad, shallow cups especially adaptable for the toy cups and 

 saucers that children enjoy fashioning from them. 



Many oaks do not begin to produce acorns until they are about 

 twenty years old. Oaks are comparatively slow-growing and long- 

 lived; you may find some that have apparently been growing for 

 several centuries. 



Oak Buds: There are noticeable differences in the shapes of oak 

 buds. On most of the white oaks they are blunt; on black oaks 

 they are large and sharp-pointed. They also differ in color. All 

 oaks do have a family resemblance, however, in the way several 

 buds, all fairly equal in size, cluster at the tip of a branch or twig. 

 (Other trees may have only one bud at, or near, the tip of the 



