_ 
PINE TREES OF ROCKY MOUNTAIN REGION. 29 
form of this pine usually designated as Pinus ponderosa scopu- 
lorum.* 
The earliest published notice of western yellow pine is in the jour- 
nal of the Lewis and Clark expedition, which records that in 1804 
cones of a pine (now believed to be western yellow pine) were found 
floating in the White River and doubtless came from a growth of 
this species in northwestern Nebraska. To David Douglas, however, 
belongs the credit of having first brought this tree to the notice of 
dendrologists by his discovery of it in 1826 on the Spokane River, 
Wash. The following year (1827) he sent seeds to the London Hor- 
ticultural Society, from which a tree was raised in the Caledonian 
Horticultural Society’s garden.? The first technical description was 
taken from this tree; and its present name, Pinus ponderosa, was 
established for the first time by Lawson? in 1836, although David 
Douglas had previously proposed this name (but without a definite 
1A long field study of the Rocky Mountain form of the western yellow pine and of the 
generally longer-leafed yellow pine of the Pacific region has convinced the writer that the 
two are geographic forms only of one widely distributed species, which was technically 
described first in 1836 as Pinus ponderosa. The Rocky Mountain yellow pine is, there- 
fore, here united as a silvical form with the Pacific slope yellow pine, under the name 
P. ponderosa. The writer can find no constant characteristics to separate satisfactorily 
the Pacific slope tree from its so-called variety “ Finus ponderosa scopulorum” of the 
central and southern Rocky Mountain region. The most distinctive types of “P. ponderosa 
scopulorum ” occur in the Dakotas, Nebraska, eastern Wyoming, adjacent sections of Colo- 
‘rado and in Texas, where the leaves are shorter and the cones smaller than are generally 
found on trees occurring west of these outlying sections. Short-leafed and small-coned 
trees are, however, not infrequent in the central and southern Rockies, along with leaf and 
cone forms that are clearly intermediate between the most eastern and the interior moun- 
tain trees. Marked differences in the soil and climatic conditions under which the short- 
leafed and the longer-leafed trees grow can easily account for the supposed specific and 
yarietal distinctions relied upon to separate the Rocky Mountain yellow pine from the 
Pacific tree. It seems much wiser to consider the trees of these two regions silvical forms 
of one variable species than to try longer to maintain them as distinct by, characteristics 
which are clearly only individual variations. Exactly parallel cases are the attempted 
separations of the Rocky Mountain form of lodgepole pine from thea Pacific coast form and 
of the Rocky Mountain form of Douglas fir from the Pacific slope form, both of which 
grow under totally different soil and climatic conditions. 
2Blwes and Henry (The Trees of Great Britain and Ireland, V, 1074, 1910). 
3 Agric. Manual, 354, 1836. The Pacific slope form of Pinus ponderosa appears to be 
well adapted to the climate of England, where, according to Elwes and Henry (opus cit., 
1076), several trees raised from Douglas’s seed, sent in 1827, and planted in 1829, were 
_ jiving in 1909 and had attained heights of from 96 to 104 feet, with diameters of from about 
26 to 35 inches. Many other trees planted since then are said to be in thriving condi- 
tion. As might well be expected, it is successfully grown there only in well-drained soils. 
The German Government in the early nineties impcrted considerable quantities of seed 
of the Pacific slope form of this tree for experiments in forest planting. The stock 
raised grew well for several years and then died from some unknown cause (Schwappach, 
Anbau. Fremdl. Holzart., 57, 1901). Presumably, however, the Rocky Mountain form 
would have proved to be adapted to German conditions. Trials of both the Pacific slope 
and the Rocky Mountain form of Pinus ponderosa in the region of New Hngland have 
not been successful (fide, Sargent, Gard. and For., 470, 1897). It is too early yet to 
predict the success of this tree set in forest experimental plantations in the Letchworth 
Park Forest and Arboretum at Portage, Wyoming County, N. Y., where so far, how- 
ever, 3 to 5 year old stock raised from Rocky Mountain seed is in thrifty condition and 
promises to grow well. A single tree now standing in the grounds of the U.S. Depart- 
ment of Agriculture, Washington, D. C., raised from seed collected in the Pacific slope 
region, was planted here about 30 years ago by William Saunders. Its growth has, how- 
ever, been exceedingly slow, the height being about 15 feet. 
