Most of the Crater Lake National Park area is occupied by the truncated cone of Mt. Mazama, the crater of which cups the lake. The basal altitude is about 4,000 feet, culminating in the higher points of the crater rim at approximately 8,000 feet. Mt. Scott on the eastern margin is nearly a thousand feet higher. For a considerable portion of the year the park is covered by snow. Even at the south entrance, which reaches the edge of the level valley, not infrequently there are remnants of snowdrifts until late in May; and not before July is the ground entirely bare on the south rim. Rarely drifts remain a month later. Consequently the flowering season is very short. Usually there are few, if any, flowers out before the first of June; and the season is practically over by the middle of September. Beginning at the lower levels, they continue up the mountain slopes following the retreating snow. In general there is a gradual replacement by other forms. Some of the lower forms, more adaptable, find themselves at home on the higher reaches. These, however, for the most part, ascend the warmer, more exposed slopes, just as plants of the upper levels tend to drop down the cold streams and shady sides of canyon walls. Radiating glacier valleys and stream-cut canyons, wet meadows, bogs, rocky walls, talus slopes, pumice flats, forest areas -- all these are among the local contributing factors in distribution and time of flowering.

Within the limits of the park there are upwards of 560 species of flowering plants. Of these there are perhaps not more than twenty-five percent which might be considered wild flowers in the more popular sense of the term. In the present account only these more showy and attractive forms are included. The first to be considered are those which are most likely to engage the attention of the average visitor, such plants are to be seen along the main thoroughfares, improved trails, about camp grounds and other more frequented places. A second group includes those found off the beaten paths and in more distant and inaccessible places, in reach of visitors who have more time and interest in plant exploration.

The growing time is so brief that it is difficult to draw the line between seasons. Late spring soon merges into early fall. By the first of August, normally, before the first flowers are gone, most of the latest plants are in bloom; thus for a short season nearly all are in flower at the same time. So in an attempt to list the plants with reference to their time of blooming, it seems convenient to divide them into two groups: (A) the earliest or lower level flowers typically associated with the ponderosa pine, as at the south entrance; and (B) the later appearing flowers of the upper slopes, characteristic of the hemlock forest area, as for example around Park Headquarters. Between the hemlock and the ponderosa pine is a more indefinite belt dominated by lodgepole pine. A similar situation exists in the more open spaces above the main hemlock belt, extending up to the highest points, such for example as Cloudcap and Llao Rock. This area is typified by the white-bark pine, a timberline tree of the higher peaks of the Cascades and other ranges. Much of the moisture is here lost in the loose soil and by the more rapid evaporation characteristic of high altitudes. These conditions limit the plants both in number of species and of individuals. While a few mat plants with well developed root systems and other adaptive features are peculiar to this windswept area, and a lesser number of the ponderosa pine association occur here, most of them are found in the main hemlock region below.

Group A

The earliest or lower level flowers typically associated with ponderosa pine, arranged in accordance with their respective habitats.

On the foregoing lists, the earliest to bloom are purple fritillary, slim solomon, Douglas phlox, gummy currant, waxy currant, serviceberry, bitter-cherry, ragwort and manzanita.

Group B

The later appearing flowers of the upper slopes, characteristic of the hemlock forest area, arranged in accordance with their respective habitats.

Among the very earliest of the last list are: yellow lambstongue, spring beauty, western windflower and alpien shooting-star.

The following list is made up of flowers not included in any of the foregoing, plants found in outlying sections not often seen by visitors. They are more common on the west slope of the Cascades, especially in the deep glacial valley of Redblanket Creek which at the southwest corner of the park drops to about 3700 feet altitude. This provides a gateway for the entrance of many west coast plants. A few of these plants reach the east side via the Klamath Gap, reaching the park up Annie and Sun Creeks.