184 . TREES IN WINTER 



Two general habit types are recognized — the spreading and the 

 erect — often termed deliquescent and excurrent respectively. The 

 former is well represented by the Apple (p. 353) and White Elm 

 (p. 327) and the latter by the Evergreens and those of the Poplars 

 that form narrow conical heads (p. 261-263). By its more erect 

 habit of growth the Sweet Cherry (p. 369) is readily distinguished 

 from the Sour Cherry (p. 371) and in like manner the Pear 

 (p. 351) from the Apple (p. 353). It is these habit differences 

 that form the most ready means of separating the contrasted 

 trees just mentioned which may closely resemble each other in twig 

 characters. The angle which the branches make with the trunk 

 is frequently a diagnostic character of considerable value. For 

 example, the ascending and gracefully outward curving limbs of 

 the American White Elm (p. 327) stand in contrast with the 

 sharply divergent limbs of the English Elm (p. 325). Likewise 

 the horizontal branches of the Tupelo (p. 421) and the strongly 

 pendant low^r limbs of the Swamp White Oak (p. 305) are char- 

 acteristic of these species. The relative thickness of the branchlets 

 contrasted in the Sweet Cherry (p. 369) and the Black Birch 

 (p. 281) and the arrangement of the branchlets whether opposite 

 or alternate and whether erect or drooping, may further be men- 

 tioned as habit characters. 



As one becomes more familiar with trees in their winter aspect, 

 the number that cannot be recognized at a distance becomes greatly 

 diminished. We come to know trees by hardly definable traits, 

 much as we recognize our friends at a distance by some peculiarity 

 of form or gait. Watching the trees from a car window is a 

 great help in acquiring this familiarity with the habit characters. 

 The method of branching and other features included in the habit 

 do not furnish such precise marks as do the twigs, and cannot 

 therefore be of much value in a descriptive key. In fact the 

 habit varies considerably among individual trees of the same 

 species, no two trees having exactly the same method of branching. 

 Moreover trees grown in woods in company with other trees are 

 prevented by lateral shading from developing their normal form 

 and produce tall trunks with but little branching. On the other 

 hand trees apart from other trees have usually been planted for 



