[Illustration: {uncaptioned}]
Long strips of land from 5500 to 8000 feet in elevation lying between
the plains and the mountains, and filling in with rough hills and
valleys the spaces between mountain ranges, comprise a life zone known
as the Foothills, and named, by naturalists, the Transition zone. In
this zone much of the soil is filled with gravel and weathered rock
detritus washed down from higher land or left there by ancient glaciers.
Total annual rainfall in this zone is higher than on the plains, and the
broken character of the land gives protection from storms.
A greater number of species of flowering plants can be found in this
zone than in any other single zone. Local conditions of soil, water and
sun exposure vary widely, and these variations offer favorable living
conditions to different types of flowering plants and to the numerous
shrubs that grow here. Many species of wild flowers which grow on the
plains extend into the lower parts of this zone, while other species
found in the higher mountains reach down into it, especially along
streams.
The chief native trees of this zone are yellow pine and, along streams,
narrow leaf cottonwood. Scrub oak covers many hillsides with dense
growth, junipers are locally plentiful, and aspens reach down from
higher elevations. This tree population attains forest proportions only
here and there so that open places for wild flowers are abundant.
In Colorado, visible spring comes earlier in this zone than on the
plains below. Sheltered slopes facing the sun pick up the earliest flush
of spring green, and by the end of March the very first flowers may here
be found in bloom. Late April, May and early June bring the main flower
crop. Mass color effects may then be found such as several acres blue
with Larkspur, or a whole hillside dotted with red clumps of Lambert’s
Loco. The main show is over by mid-July, though asters and
sunflower-like composites keep the roadsides colorful till frost.
The picture at the top of this page shows a foothills area near Golden.
In good years these hills are rich in flowers by early May. A half hour
walk then will frequently yield 30 species or more.