THE SILVA OF COLORADO 51 
with limber pine and balsam fir as secondary species. Vaccinium is 
usually abundant on the forest floor. A considerable amount of grass- 
land occurs as mountain meadows in the upper part of this zone. ‘‘ Wind 
timber” runs up in tongues to various altitudes and there are small 
patches of such scrub isolated from the main part below. Numerous 
small lakes and bogs occur along stream courses. (5) Alpine zone, 
altitude 11,500 to 14,000. This is a grassland and rock-desert zone. 
Dwarf willows occur, often in large patches, but there are no other 
woody plants. 
List oF SPECIES OF Woopy PLANTS 
PINACEAE, PINE FAMILY 
Pinus flexilis James. LIMBER PINE, WHITE PINE 
Usually a rather small tree but reaching considerable size among Engelmann spruces 
at about 10,000 ft. At lower altitudes it occurs chiefly in wind-swept stations. Easily 
distinguished from other pines of this county by its large, smooth cones and its short 
leaves in bundles of five. In exposed places it is much contorted, the trunk sometimes 
prostrate. 
Altitude: 7,500 to 11,000 ft. Collections: Eldora; Sugarloaf; Ward. Isolated 
specimens of this pine probably occur as low as 6,500 ft. where much exposed to wind. 
Pinus murrayana ‘“‘Oreg. Com.’”’ LODGEPOLE PINE 
A slender medium-sized tree forming dense, pure forests at altitudes of about 8,000 
or 9,000 ft. It also occurs mixed with the rock pine and limber pine in some places. 
Leaves are in bundles of two, the cones small and numerous. Used for fuel, timber, 
posts and railroad ties. 
Altitude: 6,500 to 10,500 ft. Collections: Allenspark; Eldora; Pine Glade School. 
Pinus scopulorum (Englem.) Lemmon. Rock PINE 
A handsome spreading tree, the largest of our native conifers. This is the only pine 
on the mesas and lower foothills in the county. Formerly much used for lumber but 
the supply in Boulder county now nearly exhausted. The lumber is known locally as 
“native” and “black jack.” Easily distinguished by its long leaves, 1 dm. or more in 
length. The leaves are in bundles of two or three. 
Altitude: 5,000 to 9,000 ft. Collections: Eldora; Sugarloaf; Bluebell Canyon; 
head of Gregory Canyon, altitude 7,400 ft. 
Picea parryana (Andree) Sarg. BLUE SPRUCE, SILVER SPRUCE 
A handsome, ornamental tree sometimes with silvery bloom especially on the leaves 
at tips of branches. It should be noted, however, that the Engelmann spruce and the 
Douglas spruce frequently are “blue’’ also. Moist situations along streams throughout 
the county within its altitudinal limit. The blue spruce never forms forests but occurs 
in fringes along streams or sometimes in small groves. Much planted for ornament. 
Altitude: 6,500 to 10,500 ft. Collections: Fourth of July Mine; South Boulder 
Canyon, altitude, 6,800 ft. 
