68 The Plant World. 



to 1.4 inches in spring to .6 to .8 of an inch at the end of the sea- 

 son. The occurrence of the bare space, however, is not to be 

 considered a result of the lack of whorl development.for the same 

 character was found as a stand characteristic in portions of both 

 the Oro Blanco and the Huachuca mountains. In certain stands, 

 noticeably near Haystack Picacho in the first named mountains, 

 all trees up to and including the oldest veterans showed trimmed 

 Itahan garden effect; other stands had only one-fifth to one-third 

 of the treei so developed; in still other stands only rare trees 

 showed anv such effect. Cross sections of the bare spaces on 

 the trees failing to develop whorls gave no interior indication of 

 where the whorls ought to be. 



Most of these trees showed a single branch coming out after 

 two or three vears' failure to produce a whorl. This branch in 

 turn might or might not produce an occasional branch at the 

 end of a year's growth. In one case such a branch appeared 

 to come from the middle of the season's growth while in another 

 case such a branch showing three years without whorls appeared 

 at the base of a tree among a large number of normal whorls. 

 It should be remembered in this connection that all four species 

 of the pinon pines have a strong tendency to produce only one 

 or two branches in a whorl and this is especially true of Mexican 

 pinon along the international boundary. In the eighteen ab- 

 normal trees the leaders were only slightly smaller in diameter 

 than on normal trees but on the other hand appeared to have 

 made a more vigorous height growth. Two of these trees with 

 a height of 7.3 feet and 8.1 feet had made a height growth of 

 4.0 and 4.1 in the last five years when whorls were not being de- 

 veloped. 



Two white fir trees respectively three and four feet tall were 

 also found in these mountains showing three years' growth with- 

 out any whorl development. These trees occurred several miles 

 apart and both grew in the open on moist, rich sites. Up to the 

 last three years the development of whorls had been normal, 

 with four to seven branches at a whorl. Prominent features 

 of both trees were the large, well developed buds scattered along 

 the leaders above t^e last whorls, shoiter needles than on nor- 

 mal trees or on whorls of the same tree, and fewer needles than 

 occur normallv on the internode. Above the whorls the needles 



