The Yosemite ferns, forests, and flowers are growing almost
exclusively in glacial soil. Nearly all of the soil in the Park is
rock-flour that was ground by glaciers, and in part distributed by
them. Landslides and running water distributed most of the remainder.
The Park has an altitudinal range of nearly two miles, with them any
climates, and consequently numerous varieties of flora. These are
encouraged by varied life zones that result from combinations of sunny
and shady mountain-sides, unevenly distributed moisture, and the
different temperatures that prevail between the altitudes of three
thousand and thirteen thousand feet.
Here and there in the Park wild flowers may be found in bloom every
month of the year. Among the common flowers of the middle and lower
sections are seen the shooting-star, evening-primrose, tiger lily,
yellow pond-lily, Mariposa lily, black-eyed Susan, lupine, paintbrush,
yarrow, and snow-plant. There are violets, blue and red, a number of
pentstemons, the lark-spur, golden-rod, several orchids, and the wild
rose.
Many of the showy, crowded gardens of luxuriant wild-flower growths
are in the moist fir forests. Among the tall flowers in these gardens
are columbines, larkspurs, paintbrushes, lupines, and one of the lily
families. The famous, fragrant Washington lily brightens the open
woods; in places it grows to the height of eight feet.
The snow-plant is a curiosity and attracts by its brilliancy of color.
The plant and bloom are blood-red, but this herb is as cold and rigid
as an icicle. It is not a parasite, but is isolated and appears to
hold itself aloof from all the world. When caught by late snows it
makes a startling figure, but it does not grow up through the snow.
In the alpine heights are many healthy plants: the lovely arctic
daisy, phlox, gentian, lupine, potentilla, harebell, mountain
columbine, astragalus, and numerous other bright flowers. They grow in
clusters and in large ragged gardens, and in places are low-growing
and extremely dwarfed.
Besides its wild small plants and the blooming shrubbery the Park has
a glorious wealth of tree blossom. The hemlocks, pines, firs, and
spruces have a jeweled wealth of blue, purple, red, and yellow bloom.
May and June are the months most crowded with blossoms, but many come
in the autumn, mingling serenely with the calm, sunny days, the
evergreen groves, the tanned grass, and the masses of red and yellow
leaves. In May and June the waterfalls are at their best, and the
birds are most songful.
The Yosemite National Park is perhaps the most delightful region
in all the world for the study of plant life. The wide variety of
conditions here found, ranging from the hot and desiccated slopes
of the brush-clad foothills to the cold, bleak summits above
timber line, the abode of glaciers and perpetual snow, gives to
the flora an exceedingly diverse and interesting character.
Innumerable springs, creeks, rivers, ponds, and lakes provide
suitable habitats for moisture-loving plants. Rocky outcroppings,
enormous cliffs, and gravelly ridges accommodate species adapted
to such situations. The irregular topography yields southward
facing slopes which receive the full effect of the sun's rays, as
well as northward slopes where the sun's rays are little felt,
where it is therefore cool, moist, and shady. The altitude ranges
from two thousand five hundred feet in the foothill belt to
thirteen thousand and ninety feet along the crest of the Sierra
Nevada. All of these factors conspire to produce a remarkably
varied and interesting vegetation.
The richness of this flora is indicated by the nine hundred and
fifty-five species and varieties here described. The total number
represented in the Yosemite National Park is considerably greater,
since the grasses, sedges, and rushes are here omitted. Including
an estimate for these, it is safe to assume that the number of
species and varieties of flowering plants and ferns to be found
within the one thousand one hundred and twenty-four square miles
of the park is not less than about one thousand two hundred. ("A
Yosemite Flora," by Harvey Monroe Hall and Carlotta Case Hall.)