TREES IN WINTER 



81 



sap as in the mulberries. If the twig 

 is cut off sharply at right angles the 

 generally star-shaped section of the 

 pith suggests an oak. As the round 

 sectioned pith is so common it is not 

 of much use as a mark of identifica- 

 tion. But if a twig is cut longitu- 

 dinally through the center of the pith 

 a new set of characteristics is dis- 

 played. The pith may be solid or 

 continuous as in the great majority 

 of trees. But it may be chambered, 

 that is, consist of transverse divi- 

 sions or diaphragms separated by 

 empty spaces. There are but three 

 large forest trees common in the cen- 

 tral states that have chambered pith. 

 It is frequently disguised and hard to 

 recognize in the hackberry, but it is 

 very plain and evident in the walnut 

 and butternut. The color and the 

 spacing of the diaphragms instantly 

 distinguish a walnut from a butter- 



f!F,^*( 



nut. In many respects the twig of 

 butternut (a walnut) resembles the 

 twig of bitternut (a hickory.) A 

 glance at a section of the pith imme- 

 diately differentiates them. The but- 

 ternut pith is brown and chambered, 

 the bitternut pith is brown and not 

 chambered. 



Though I have spoken of the pith 

 first it is the least important element 

 in the winter identification of trees 

 by means of the twig. It is on the 



i 



FLOWERING DOGWOOD 



The (logwood, its bark characteristically 

 divided into squares, is readily recognized 

 by the visitor to the winter woods. 



HOP HORNBEAM 



The bark is gray-brown, scaly and scored 

 perpendicularly into long, flat narrow 

 strips about four inches long. 



epidermis, or outside skin, that we 

 mostly depend. 



Twigs are rough or smooth. They 

 may be of almost any color, varying 

 from the bright green of the sassa- 

 fras, the brilliant yellow of the golden 

 willow, through various reds, browns, 

 grays and black. Twigs are some- 

 times smooth, or hairy, or ridged, or 

 winged. The square section of the blue 

 ash twig immediately distinguishes it 

 from the other ashes. While the flat- 

 tening of the twig at the node pre- 

 vents us from confusing an ash with 



BUR OAK 



Known also as Mossy Cup Oak. It has an 

 ashen gray, or gray-brown, thin, scaly bark. 

 It is one of the tallest oaks in the eastern 

 United States. 



any other tree. We have, however, 

 hardly made a beginning in the enu- 

 meration of the differentiating charac- 

 teristics of the twig. Every leaf 

 which fell in the autunm left a scar 

 on the twig. If the leaf scars of a 

 large tree are opposite we may be 

 reasonably sure that the tree is a 

 buckeye, an ash, or a maple. And 

 there are but a few low, or shrub-like 

 trees that present this characteristic. 

 If the scars are not opposite their ar- 

 rangement may still be very helpful. 

 The leaves may originally have been 

 attached to the stem in such a way 

 that the twig has remained straight, 

 or attached in another way which pro- 

 duced a twig elongating in a zig-zag 

 fashion. 



Furthermore, the outline of the scar 

 is characteristic. In the maples it is, 

 generally speaking, crescent shaped, 

 in the catalpa oval, in the walnut 

 heart-shaped, etc. But there are finer 



