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INTRODUCTION TO CALIFORNIA DESERT WILDFLOWERS
By PHILIP A. MUNZ
The University of California PressRegents of the University of California
All right reserved.
IntroductionThe California Deserts
The California deserts comprise a considerable area if we include the region below the yellow pine belt (Pinus ponderosa), beginning in the north with the lower slopes of the Sierra Nevada and a large part of the Inyo and White Mountains and their environs and ending in the south with the Imperial Valley and the arid mountains to the west and the sandy region toward the Colorado River. Roughly, and for practical purposes, we can think of our desert as consisting of (1) the more northern Mojave Desert reaching as far south as the Little San Bernardino and Eagle Mountains and the ranges to the east and (2) the more southern Colorado Desert. Being quite different from each other, these two deserts are worth short separate discussions.
In the first place, the Mojave Desert, except for the Death Valley region and the area about Needles, lies mostly above 2,000 feet. Hence, it has more rainfall and colder winters. It opens out largely toward the northeast and in many ways is an arm of the Great Basin of Utah and Nevada, and its plant affinities often lie in that direction. The Colorado Desert, on the other hand, consists largely of the Salton Basin, much of it near or below sea level. It opens toward the southeast, and itsaffinity floristically is with Sonora, and it is often placed as part of the Sonoran Desert. Not surprisingly, then, many species of the Mojave Desert extend into Nevada and southwestern Utah, whereas many of the Colorado Desert range into Sonora and western Texas. There are of course many patterns of more limited distribution, such as along the mountains bordering the western edge of the Colorado Desert from Palm Springs into northern Baja California or around the western edge of the Mojave Desert from the base of the San Bernardino Mountains to the Tehachapi region.
The climatic conditions in the desert and the situation for plant growth are severe. Plants have had to resort to interesting devices to exist at all. In the first place, seeds of many desert plants have so-called inhibitors that prevent germination unless the inhibiting chemicals are thoroughly leached out by more than a passing shower. This means that for many of them it takes a good soaking rain to get started, one that wets the ground sufficiently for the seedling to send a root down below the very surface. A second characteristic of many of the annuals is that if the season is rather dry, they can form a few flowers even in a most depauperate condition and ripen a few seeds under quite trying circumstances. Thirdly, many of those plants that do live over from year to year cut down evaporation by compactness (small fleshy leaves and reduced surface area as in cacti), by coverings of hair or whitish materials that may reflect light and hence avoid heat, and by resinous or mucilaginous sap that does not give up its water content easily, as exemplified by creosote bush (Larrea tridentata) and cacti.
A widespread popular fallacy should be mentioned. We read of the great depth to which desert plants can send their roots in order to tap deep underground sources of moisture. This situation is true along washes, watercourses, and basins, where mesquite (Prosopis glandulosa var. torreyana) and palo verde (Cercidium spp.), for example, send roots down immense distances, but in the open desert an annual rainfall of six or eight inches distributed over some months may moisten only the upper layers of soil. Therefore, shrubs such as creosote bush and plants such as cacti tend to have very superficial wide-spreading roots that can gather in what moisture becomes available.
Something should also be said about summer rains. On the coastal slopes at elevations below the pine belt, we are accustomed to summer months practically without rain. But in Arizona and the region to the east of us, there are two definite rainy seasons: one producing a spring flora and another producing a late summer and early fall crop. For the most part the annuals that come into bloom in these two distinct seasons are quite different. Many summers, the Arizona rains reach into the desert areas of California and sometimes produce veritable cloudbursts of water. At such times thunderheads appear over the adjacent mountains such as the San Bernardino, San Jacinto, and San Gabriel Mountains, and the neighboring coastal valleys are much more humid and uncomfortable than when the desert is dry. After these summer rains some of the perennials may exhibit new growth and flowering, and a new crop of annuals may appear, such as chinchweed (Pectis papposa var. papposa) and California kallstroemia (Kallstroemia californica). In the southern Mojave Desert west of Baker and Cronise Valley, I have seen the desert floor green for miles with California kallstroemia in early September.
As any desert habitue knows, plant life there is not uniform but varies with elevation, drainage, character of soil, and the like. One of the characteristic features is the presence of many undrained basins, known locally as "dry lakes," where water may gather in unusually wet years only to dry up more or less completely after a few weeks. Such a situation through the centuries brings about the accumulation of salts or alkali, making these areas too salty for any plant life, or at the fringes there may be an accumulation of species adapted to salty conditions, such as various members of the goosefoot family (Chenopodiaceae), including desert-holly (Atriplex hymenelytra) and iodine bush (Allenrolfea occidentalis). These basins are scattered over the Mojave Desert and form a series along the old channel of the Mojave River, which flows eventually into Death Valley, the largest of all. A similar situation exists in the area near the Salton Sea.
The great open plains and flats of much of the desert are covered with creosote bush (which is associated with burroweed [Ambrosia dumosa]), box thorn (Lycium cooperi), brittlebrush (Encelia farinosa), and many other species. Here the average rainfall is from two to eight inches, and summer temperatures may be very high. Some cacti grow in this region, which is mostly pretty well drained, but many are found on rocky canyon walls, in stony washes, and in other places also. In areas above the creosote bush in the Mojave Desert, say from 2,500 feet to 4,000 or higher, Joshua trees (Yucca brevifolia) tend to distribute themselves in a sort of open woodland with lower shrubs in between. Here the annual precipitation may be from six to 15 inches, and the vegetation is correspondingly richer. And then, along the western edge of the Colorado Desert and more particularly in the mountains bordering on and situated in the Mojave Desert, is a zone of pinyon and juniper, mostly at 5,000 to 8,000 feet. Here the annual precipitation runs about 12 to 20 inches a year, some of it as snow. This belt has some summer showers and some plants in bloom in summer and even fall, as well as in spring, which comes later than in the creosote bush zone. Particularly in the more northern parts of the desert, creosote bush gives way in the upper elevations to sagebrush (Artemisia tridentata and relatives), and large regions in Lassen, Mono, and northern Inyo Counties have a sagebrush desert like that of Nevada and Idaho. With so wide a diversity of conditions, then, it is not surprising to find quite different flowers at various altitudes and in various habitats.
How to Identify a Wildflower
It is impossible to talk about plants and their flowers without using some specialized terms to describe their parts. Some of the most necessary terms are explained here, and a more complete list is defined in the glossary. In the typical flower we begin at the outside with the sepals, which are usually green, although they may be colored. The sepals together constitute the calyx. Next comes the corolla, which is made up of separate petals, or the petals may grow together to form a tubular or bell-shaped corolla. Usually the corolla is the conspicuous part of the flower, but it may be reduced or lacking altogether (as in the grasses [Poaceae] and sedges [Cyperaceae]), and its function of attracting insects for pollination may be assumed by the calyx. The calyx and corolla together are sometimes called the perianth, particularly when they are more or less alike. Next, as we proceed inward in the flower, we usually find the stamens, each consisting of an elongate filament and a terminal anther where the pollen is formed. At the center are one or more pistils, each with a basal ovary containing the ovules or immature seeds; a more or less elongate style; and a terminal stigma with a rough, sticky surface for catching pollen. In some species, stamens and pistils are borne in separate flowers or even on separate plants. In the long evolutionary process by which plants have developed into the many thousands of types of the present day and have adapted themselves to various pollinators, their flowers have undergone very great modifications, and so now we find more variation in them than in any other plant part. Our modern system of classification is largely dependent on the flower parts.
To help with the identification of a wildflower, either a color photograph or a drawing is given for every species discussed in detail, and the flowers are grouped by color. In attempting to arrange plants by flower color, however, it is sometimes difficult to place a given species to the satisfaction of everyone. The range of color may vary greatly, from deep red to purple, from white to whitish to pinkish or greenish, from blue to lavender, or through a wide range of yellows and oranges, so that it presents a challenge for the writer himself, let alone the readers, to determine whether one color group or another should be used. I have done my best to recognize the general impression given with regard to color and to categorize the plant accordingly, especially when flowers are very minute and the color effect may be caused by parts other than petals. My hope is that by comparing a given wildflower with the illustration it resembles within the color section that you think is most correct and then checking the facts given in the text, you may, in most cases, succeed in identifying the plant.
One of the chief difficulties in writing such a book is to find usable common names. I am not interested in taking those coined from the scientific name by a professional botanist who breaks down the genus name into its Greek roots and then adds the species name, such as, for example, the common name Mrs. Ferris's club flower for Cordylanthus ferrisianus. On the other hand, if the local inhabitants call this bird's beak, that is acceptable. For some plants, however, I may have been unable to ascertain a true folk name. In these cases it has seemed best to me to use the genus name, such as Phacelia or Oxytheca, as a common name too. Many desert plants are not very conspicuous and just do not have good, widely used names, so we have to resort to this scientific appellation.
Another problem I confronted is which plants to present. I have tried for the most part not to include those already shown in California Spring Wildflowers, so that anyone having both books has that many more species shown. I have chosen plants that I feel are interesting, but not all are necessarily showy or common. I have attempted not to present the various closely related forms of a complex group but have taken one as an example and often added a word about additional forms closely resembling the first. I have tried, too, to include species from the different parts of the desert so that the book is useful for more than just the Palm Springs region, for example, or just Death Valley, to name two of the commonly visited areas.
I cannot help but register a plea that residents of the desert and visitors thereto exercise discretion in picking, transplanting, and otherwise interfering with normal development and reproduction of desert plants. The thousands of people who live in or visit the desert nowadays are bound to inflict hardship on the vegetative covering. With the scant rainfall, desert plants grow slowly, and a branch broken off a pinyon tree for a campfire may have taken many years to produce. Certainly those who have known the desert over a period of years cannot help but be appalled by the magnitude of the recent destruction.
Philip A.Munz Rancho Santa Ana Botanic Garden Claremont, California June 1, 1961
INTRODUCTION TO THE PLANT COMMUNITIES OF CALIFORNIA'S DESERTS
The word "desert" brings to mind dry, hot, harsh landscapes that scarcely support living beings. By definition, deserts are harsh environments, but California deserts support a surprisingly rich diversity of plants and animals. Three major deserts occur in the state: the Mojave Desert, the Colorado Desert, and the Great Basin Desert. The wildflowers described in this book grow in the first two deserts. Plants of the Great Basin Desert, found east of the Sierra Nevada and Cascade Range crests, are not included. Philip Munz's introduction to the first edition of this book, which is reproduced here, describes the location of the Mojave and Colorado Deserts in California, gives a brief account of their climates, and presents a synopsis of representative adaptations of the plants that live in these extreme environments.
The term "desert" has no precise definition; a desert is simply an area with low average annual precipitation. Deserts may occur along coastlines, in interior regions, at the poles, or on mountaintops. They may be very local, lying in the rain-shadows of mountains; they may occupy the uppermost peaks of mountains; or they may extend over many thousands of square miles, as does the Colorado Desert, which is a northwestern extension of the vast Sonoran Desert. Portions of the Mojave and Colorado Deserts receive an annual average precipitation of four inches or less. In places, some years pass with no measurable precipitation. In parts of our deserts, rainfall is mostly limited to winter months, but in other areas there are two peaks of rainfall-one in winter and another in summer. The Mojave and Colorado Deserts have high numbers of sunny days during the year-commonly more than 300 days per year are cloudless or nearly so. Summers are hot, with 150 days or more having maximum temperatures exceeding 90 degrees F. Death Valley may be the hottest place on earth-a maximum temperature of 134 degrees F has been recorded there. Winters in our deserts generally are mild. The Mojave Desert is wetter and cooler than the Colorado Desert because it occupies higher elevations. It may even experience frosts or light snowfall during winter. The Mojave Desert occupies about two times more area in California than does the Colorado Desert.
Plants that grow in deserts must be able to survive extended drought and low annual precipitation and must be able to survive relentless heat and intense sunlight. California deserts by no means offer a uniform environment. Soils vary from place to place, and there are local occurrences of gypsum, alluvial fans, dry washes, oases, and soils with various levels of salinity. As one ascends desert mountains or descends into desert valleys, climatic and soil conditions change in relation to elevation, and these changes are reflected by differences in vegetation types and plant communities. The higher elevations may support juniper and pinyon pine woodlands; the lowest elevations are often highly saline and support only a few plant species. In low areas where the soils are moderately saline, low shrubs with intriguing names such as winter fat (Krascheninnikovia lanata), burrobush (Hymenoclea salsola), and hop-sage (Grayia spinosa) predominate. In even lower, highly saline areas that are the dry beds of former Pleistocene lakes, alkali sink scrub predominates. Here one finds the odd succulent shrub called iodine bush (Allenrolfea occidentalis) (because its sap stains human skin brown) and the equally succulent pickleweed (Salicornia spp.). The prominent American botanist T.H. Kearney once wrote of these shrub-dominated communities that "no other vegetation ... gives the impression of being so nearly conquered by the environment," and even Philip Munz, author of this book, admits that these shrublands cover "large monotonous areas." Yet many visitors to the desert find this so-called monotony appealing and come back every year to enjoy its peaceful visual simplicity.
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Table of ContentsEditor’s Preface to the New EditionPhyllis M. FaberAcknowledgmentsIntroductionIntroduction to Desert Plant CommunitiesMap of Desert RegionsFerns and Fern AlliesReddish Flowers: Rose to Purplish Red or BrownWhitish Flowers: White to Pale Cream or Pale Pink or GreenishBluish Flowers: Blue to VioletYellowish Flowers: Yellow to OrangeGlossaryArt CreditsIndex
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