Part 1

COLORADO WILD FLOWERS

MUSEUM PICTORIAL

ROBERTS

Copyright 1953, by Denver Museum of Natural History, Denver, Colorado

Lithographed in the United States of America by Bradford-Robinson Printing Company, Denver, Colorado

Acknowledgments:

The original color films used for the plates on pages 15 and 26, were heretofore reproduced in different form in “American Wild Flowers”—Moldenke, published in 1949 by D. Van Nostrand Co., New York, with whose permission they are again reproduced here.

The pen and ink diagrams and sketches on pages 3, 60, 61, 62 and inside back cover, were prepared by Mary Chilton Gray, of the staff of Denver Museum of Natural History.

Lily Family Yucca or Spanish Bayonet, Yucca glauca, NUTT.

⇐FRONT COVER

Flowers, closely arranged along a tall woody bloom stalk, are each formed by 6 petals and sepals (perianth segments) surrounding a large fleshy pistil. The 3 outer segments often have mahogany brown shading on the back, the 3 inner are creamy white, or greenish white. They look like drooping bells in the daytime, but spread to a total width of 3 to 4 inches when fully open in late evening. Pollination is accomplished only by the deliberate work of a Pronuba moth. Total height of plant, including blossom stalk, is about 4 feet; leaves narrow, stiff and yellowish green, with a sharp spine at tip. Grows on plains, particularly in sandy areas, and extends into foothills. Blooms June-July.

SOME COMMON COLORADO WILD FLOWERS

By Harold and Rhoda Roberts

FOREWORD

The generous acceptance of the first seven numbers of MUSEUM PICTORIAL convinced the Trustees of the Denver Museum of Natural History that the publication is filling a definite need in the field of natural history reports. The subjects are so varied that a wealth of material is available.

The present issue is the first printed in color, and will, we hope, be followed by others. The authors, Harold and Rhoda Roberts, probably are the foremost photographers of wild flowers of Colorado and the Southwest. This field work has carried them from the tops of the highest mountains of Colorado to the depths of Death Valley. Their outstanding Kodachrome slides have been shown to many audiences and have appeared in publications. It is hoped that Museum Pictorial No. 8 will be the first of a series on Colorado wild flowers by the authors, which may eventually be compiled into book form.

Harold Roberts, prominent Denver attorney, is a Trustee of the Museum, and chairman of its Building Committee.

Alfred M. Bailey, Director

Museum Pictorial No. 8 Published May 30, 1953 Denver Museum of Natural History Denver, Colorado

The purpose of this booklet is to portray a few of the common wildflowers of Colorado in such form that they may be recognized and their names learned without the use of any botanical key. The color plates here published show fifty different flowering plants, each of which grows in abundance in some part of this state. Most of them are found also in other areas, particularly in the Rocky Mountain states. With the description of each plant, some reference is made to the life zone in which it grows, but no attempt is made to give the geographical extent of its range. In every instance the photograph reproduced was taken on Kodachrome film of a living plant in its natural setting. All of them are shown in full bloom as we see them in Spring or Summer, except milkweed, page 43, and cattail, back cover. These appear in seed as we find them along the roadsides in October.

The flowers are here arranged in substantially the order that the families to which they belong appear in most botany manuals. Some references to these plant families, and to the genera and species into which they are subdivided, will be found on page 57. With each plant we have given the common name most familiar to us. As there is little uniformity in common name usage, others may know them by other names. We have added in each case, in italics, the Latin botanical name, with abbreviated identification of the botanist first using that name. The English form of the family name is also given. We have tried to select flowers representing as many plant families as possible, and among them to cover plants from different altitudes and from different types of soil and growing conditions.

Some of these photographs were taken at close range, with a long focal length lens, to show on a large scale the beauty of very small flowers. Others were taken with different equipment so as to include the form of the complete plant and show plainly its natural setting. In all cases the size of the flower and of the entire plant are given in or may be inferred from the descriptive text. The figures used are approximate, and considerable variation from these sizes will be found. The colors are as accurate as colorfilm and high class press work can make them.

The pictures here reproduced were all taken by the authors within the past twelve years. Most of the plants were found within a few hundred feet of some well traveled road. A few of the pictures were taken in adjoining states, but in every such instance the species shown is found in the same sort of environment in Colorado. Many of these flowers are reproduced as part of the setting in habitat life groups in the Denver Museum of Natural History. Look for them there, and also get acquainted with them in their native haunts. They add decided interest to outdoor ramblings.

LIFE ZONES

14,431′ Alpine 11,600′ Sub-Alpine 10,000′ Montane 8,000′ Foothills 5,500′ Plains 3,500′

Climate, which is a composite of prevailing temperature, length of season and average moisture, is the chief factor in deciding where plants of any given species can grow and propagate. Soil type also plays a part, and if extremely unfavorable may totally exclude some species of plants from a large and otherwise favorable area, but in general, soil is the minor factor. In Colorado, climate is largely determined by altitude, so here, as we pass from one elevation to another, we find plant life arranged in horizontal layers or zones of the sort illustrated in the above sketch. The thinness of air, in the sense of less oxygen per cubic foot of air, that goes with high elevation, seems in itself to have little effect on plant life, but the prevailing cold, the long period of snow cover, and the increase in annual precipitation, that go with elevation in our mountains, do have a profound influence on plant growth. High latitude has much the same effect as high altitude, so that the timberline conditions we find in Colorado at from 11,000 to 12,000-foot elevations are very similar to those existing at sea level near the Arctic Circle. Growing conditions, and prevailing plant species, at these widely separated places, are, for this reason, much alike.

These zones of life have no sharp boundaries, but tend to intergrade into each other. Many species of plants normally inhabit parts of two or more zones, and local conditions may so influence climate that particular species of plants will be found growing at lower elevations, or at higher, in one part of the state than in another. Generally, however, in Colorado like elevations result in plant populations of quite similar makeup, even though a whole range of mountains or a deep wide valley may lie between. The principal factor causing exceptions to this rule is the tendency of many areas in western Colorado, particularly those between about 6,000 and 10,000 feet in elevation, to receive greater average annual precipitation than is received by corresponding areas east of the Continental Divide. As a result of this, many species which in eastern Colorado occur only in moderately high elevations will be found clear down in the foothills in western sections.

The individual life zones of Colorado are illustrated and described on the next five pages.