Brigham Young University BYU ScholarsArchive Theses and Dissertations 1967-07-28 A flora of the Beaver Dam mountains Larry Charles Higgins Brigham Young University - Provo Follow this and additional works at: https://scholarsarchive.byu.edu/etd BYU ScholarsArchive Citation Higgins, Larry Charles, "A flora of the Beaver Dam mountains" (1967). Theses and Dissertations. 8071. https://scholarsarchive.byu.edu/etd/8071 This Thesis is brought to you for free and open access by BYU ScholarsArchive. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. ,/ 1/~, ; /."' ' / __.,,/ A FLORA OF THE BEA VER DAM MOUNTAINS A Thesis Submitted to the Department 0£ Botany Brigham Young University Provo, Utah In Partial Fulfillment of the Requirements for the Degree Master of Science by Larry C. Higgins August, 196 7 This thesis, by Larry C. Higgins, is accepted in its present form by the Department of Botany of Brigham Young University as satisfying the thesis requirement for the degree of Master of Science. ii ACKNOWLEDGEMENTS The author wishes to extend his gratitude to all those who have helped to make this work possible. The author would first like to extend his gratitude to Dr. S. L. Welsh of Brigham Young University for his counsel and guidance in the selection of this study. The author is also indebted to Dr. B. F. Harrison of Brigham Young University for the identification of the grasses, to James Reveal for the identifrcation and key to the genus Eriogonum, to Dr. Andrew Barnum of Dixie Junior College for the use of that institution's herbarium in the study of many of the specimens. The author also wishes to express his appreciation to his good wife, who worked to support the family making it possible to continue in school, also for her help in typing parts of the manuscript. The author is also grateful to Monte Burton for the use of his pickup making it possible to travel many of the rough mountainous roads which would otherwise be impassable. iii TABLE OF CONTENTS Page ACKNOWLEDGEMENTS. iii INTRODUCTION. l Statement of the Problem Review of Literature Geographical Description of the Beaver Dam Mountains Procedure Ecology Geology Arrangement of Keys and Plant Families KEY:J AND DESCRIPTIONS. 8 Key to the Families of Plants. 8 Equisetaceae. 24 Polypoaiaceae . 24 Pinaceae ... , . .. 27 Cupressaceae. 29 Ephedraceae. , . 31 Typhaceae. 32 Gramineae ...................... 32 Cyperaceae. 64 Juncaceae. 65 Liliaceae. 66 Agavaceae. 71 Orchidaceae. 72 Saururaceae. 72 iv Salicaceae. 7 Fagaceae. 7 Ulmaceae. 7 Urticaceae. 7 Loranthaceae .. 7 Santalaceae. 7 Polygonaceae. 7 Chenopodiaceae. 9 Amaranthaceae. 10 Nyctaginaceae. 10 Portulacaceae. 10 Caryophyllaceae. 10 Ranunculaceae. 10 Berberidaceae. 11 Papaveraceae. 11 Fumariaceae. 11 Cruciferae. 11 Capparidaceae. 13 Saxifragaceae. 13 Rosaceae. 13 Leguminosae. 13 Krameriaceae. 15 Geraniaceae. 15 Linaceae. 15 V Zygophyllaceae. 156 Rutaceae. 157 Simarubaceae. 158 Polygalaceae. 159 Euphorbiaceae. 159 Anacardiaceae. 162 Celastraceae. 162 Aceraceae. 163 Meliaceae. 163 Rhamnaceae. 164 Vitaceae. 164 Malvaceae. 165 Tamaricaceae. 167 Loasaceae. 168 Cactaceae. 171 Onagraceae. 178 Umbelliferae. 185 Garryaceae. 188 Ericaceae. 188 Loganiaceae. 189 Oleaceae. 189 Gentianaceae. 191 Apocynaceae. 193 Asclepiadaceae. 193 vi Convolvulaceae. 196 Polemonaceae. ' . .. 197 Hydrophyllaceae. 205 Boraginaceae. 213 Verbenaceae. 223 Labiatae .. 224 Solanaceae. 229 Ser ophulariaceae. 232 Bignoniaceae. 241 Martyniaceae. 242 Orobanchaceae. 242 Plantaginaceae. 243 Rubiaceae. 245 Caprifoliaceae. 246 Cucurbitaceae. 248 Campanulaceae. 248 Compositae. 248 SUMMARY ..... 303 LIST OF REFERENCES. 305 vii INTRODUCTION Statement of Problem This investigation of the flora of the Beaver Dam Mountains was undertaken because no previous attempt had been made to study the plants of this unique region intensively. The Beaver Dam Mountains are located in southwestern Washington County, Utah, and northwestern Mohave County, Arizona. This area is unique because approximately fifty percent of the plants found on this mountain range are from the Lower Sonoran life zone. This life zone enters the state of Utah only in southwestern Washington County. Plant species are also well represented from the Upper Sonoran and Transition zones from the north. Review of Literature The first record of botanical collecting in the Beaver Dam Moun- tains is by C. C. Parry in 1874 (from Parry's collections on loan from Iowa State University). Dr. Edward Palmer visited the mountain in 1877 and collected Astragalus preusii Gray var. laxiflorus Gray ,(not found there again since the original collection). During April of I 880 Marcus Jones collected in the Beaver Dam Mountains (Jones, 1965). Merriman and Bailey, members of the Death Valley Expedition, were in the region from May 6th to the 16th in 1891 (Coville, 1893). They collected about fifty plants. I 2 Dr. W. P. Cottam collected in the Beaver Dam Mountains exten- sively in 1927, 1929, and 1940 {fide her barium specimens, Bry), where he worked extensively, mainly in the region of the Virgin Narrows. The work by Cottam was the most extensive prior to the present work. During the year of 1941 Bassett Maguire and.his students from Utah State Agriculture College spent a few days collecting near Welcome Spring. During the same year B. F. Harrison collected many plant specimens from the vicinity of the Beaver Dam Mountains. During the years that followed many small groups from Utah State University, University of Utah, Brigham Young University, Snow College, and Dixie College have collected plants from the area. The writer collected in the Beaver Dam Mountains in 1961, and throughout the growing season in 1966. Geographical Description of the Beaver Dam Mountains The Beaver Dam Mountains are located in the extreme southwest- ern corner of Utah and the northwestern corner of Arizona. The Utah portion of the range makes up about three-fourths of the area. ) The mountain rises gradually from the Beaver Dam Wash' on the west and the Santa Clara River on the east to an elevation of 4,500 feet. 7~0:J /'{I· It then rises abruptly to an elevation of 7,000 to 8,000 feet with many high cliffs and rocky ridges. On the south end of the range the Virgin River has cut a deep gorge, the Virgin Narrows, with sheer cliffs several hundred feet high, adorned with hanging gardens. The area covered in this study is approximately thirty miles in length and twenty miles wide. It is bounded on the west by the Beaver 3 Dam Wash, on the north by the Jackson road, on the east by the Santa Clara River, and on the south by the Virgin River. Procedure -Field work was begun February, 1966, and was continued until October of the same year. Field trips were made every two weeks dur - ing this period. An attempt was made to collect and classify all of the vascular plants which occur on the Beaver Dam Mountains. All speci- mens collected are deposited in the herbarium at Brigham Young University. On each of these field trips the author attempted to cover the mountain range as thoroughly as possible, from the Beaver Dam Wash at an elevation of 2, 300 feet to the highest elevation at 7, 800 feet. < A study was made of all pertinent specimens in the herbaria of Brigham Young University and Dixie College. Ecology The vegetation of the Beaver Dam Mountains can be divided into several major plant communities. These communities are not entirely uniform, but they are indicative of certain edaphic and climatic conditions. Larrea tridentata and Franseria dumosa community. The shrubs from which the Larrea-Franseria Belt derives its name. The plants are widely spaced on the bajadas and the lowest foothills in the hottest and driest desert conditions. They are occasionally replaced locally by other desert shrubs. 4 Coleogyne ramosissima community. This community occurs at elevations of 2, 600 to 4, 500 feet on limestone soil, and forms a very conspicuous zone. In many places Yucca brevifolia, Yucca baccata, and Opuntia acanthocarpa are also part of this community. Artemisia tridentata community. Artemisia tridentata, abundant in the northern Great Basin, is frequently used as an indicator of the Upper Sonoran life zone. In the Beaver Dam Mountains it is widely scattered, and it is abundant only locally. It is found to elevations of about 7,500 feet, where it grows on soils derived from limestone. Quercus turbinella community. This community occurs primarily on sandstone soils at elevations of 2, 500 to 3, 000 feet. These plants are either shrubs or small trees and are uncommon on the major limestone outcrops of the Beaver Dam Mountains proper. Juniperus osteosperma and Pinus monophylla community. The trees of the Juniper-Pinyon zone are usually small trees found at elevations of 4,000 to 7,500 feet, where they grow on calcareous soil. Juniper and Pinyon are generally found growing on the southern exposure and form a conspicuous part of the vegation of the Beaver Dam Mountains. Amelamchier utahensis community. This community occurs on the north-facing slopes at the same elevation as Juniper and Pinyon. The dense stands occur on limestone soil and are commonly associated with Quercus gambellii. Pinus ponderosa community. Ponderosa pine is our largest tree and is dominant on limestone soils above 7, 500 feet elevation. Undoubt- edly the size and cover of this plant provides good cover and tends to 5 reduce evaporation. This