352 PROCEEDINGS OF THE ACADEMY OP 



If the parent plant V)e cut leaved, of course the wliole is a cnt- 

 leavod dump. If entire leaved, we have an entire-leaved clump. 

 If not of very vigorous growtli, we have a clump of vegetation not 

 moie than two or three feet high ; and then we have a mass of 

 vigorous growers ; one of the latter in Cheyenne Canon, south of 

 Pike's Peak, he saw with numerous little trees, perhaps thirt3' feet 

 high, and stems two feet in circumference. There appeared no- 

 where, in his many hundred miles of travel, any young seedlings ; 

 indeed no plants anywhere that were probably less than twenty- 

 five years old ; and yet, in both of his visits to these regions, the 

 plants were bearing acorns in the greatest abundance, and evi- 

 dently bore in this way every _year. 



The coniferous trees of this region present the same appearances. 

 Of some species 3'oung ones are rarely seen. This is especially 

 true of Pinus ponderosa, which is perhaps more widely distributed 

 through the Rocky Mountains than any other. The greater num- 

 ber of these trees are between one and two hundred years old. A 

 stump of one of the largest cut down in Williams' Canon, near 

 Colorado Springs, had 216 concentric rings. Young broods of 

 perhaps ten or twenty years old are occasionally seen, but not 

 often. The young broods throughout the region between Gray's 

 Peak and Pike's Peak are chief!}' of Pinus contorta, or, as it ought 

 perhaps to be more properly called, Pinus Balfouriana. Sometiuies 

 hundreds of acres of perhaps ten, twenty, or thirty years would be 

 met with, but always of the same age in one district. Of course, 

 where this species follows Pojndus tremuloide^^ as it often does 

 when the i)oi)lar has been burned off, it is easy to understand how 

 the pines may be all of one age ; but the uniformity is the same 

 whether the pines follow a burned district or not. Abies graudis 

 affords the greatest irregularity in ages; but this, so far as his 

 observations went, made no separate forests, but were mostly 

 mixed with other species, chielly with Abies Douglassii, Abies 

 Mensiesii, or Abies Eiigelmannii. The general rule was evident 

 everywhere, that only on special occasions, and these apparent!}' 

 oiten at long intervals, did a crop of young coniferous trees ai)pear. 



These facts l)eing gained, we can understand at least some of the 

 influences at work to prevent the spread of timber on the prairies 

 from the trees growing along the river banks, or on to the low 

 lauds IVom the timl)ered regions on the heights. If under the most 

 favorable conditions in the East, and on the cool slopes of moun- 

 tains, it is but oecasiomdly that the seeds find a conjunction of 

 elements favor'alile to successful growth, how much more rare must 

 these circumstances be on a dry, hot prairie? Seeds ma}' fall for 

 ao^es alons: the line of a river, and yet not a tree be found a hun- 

 drcd yards from the river line. 



lie lliouglit, also, the facts would account for what is known as 

 the timber line in the Rocky Mountains. This was not an arbi- 

 trary division, decided by mere altitude, as was populary supposed; 



