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1936 Notes to accompany a vegetation map of northwest Mexico Donald Dilworth Brand

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Recommended Citation Brand, Donald Dilworth. "Notes to accompany a vegetation map of northwest Mexico." University of New Mexico biological series, v. 4, no. 4, University of New Mexico bulletin, whole no. 280 4, 4 (1936). https://digitalrepository.unm.edu/unm_bulletin/26

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I, I, ' 1'1 The University of New Mexico I II Bulletin I, 'I • 'Ii ,I I ,I I I, NOTES TO ACCOMPANY A VEGETATION MAP OF I" NORTHWEST MEXICO

DONALD D. BRAND.

THE UNIVERSITY OF NEW MEXICO BULLETIN Whole Number 280 Janu'ary 15,.1930 Biological Series, Vol. 4, No. 4 . Published twice a month by the University of New Mexico Albuquerque, New Mexico Entered' as Second Class Matter, May I, 1906, at the post office at Albuquerque, New Mexico, under Act of Congress of July 16. 1894 UNIVERSITY OF NEW MEXICO PRESS 1936 PREFACE The following map and notes are based upon field notes made by the writer during the years 1929-1931, while in northwest Mexico, under the auspices of the University of California Department of Geography.. In 1934 and 1935, the Border regions' of Baja California, Sonora, and Chi­ huahua were revisited. What ever of accuracy and of value there may be in these notes is derived from the instruction in plant geography by Professor William A. Setchell, and in, field methods by Professor Carl O. Sauer. All available literature has been checked to verify and amplify the field notes. At the moment, this paper constitutes the most com­ plete summary of the literature and knowledge concerning the vegetation of the area involved. It is hoped to follow ' this paper, at some time in the future, with a monograph on the climates of northwest Mexico, which will help in. the interpretation of areal distributions of associations and formations.

[ 3 ] TABLE OF CONTENTS Page Preface 5 Introduction _~ ~~~~ ~ 7 Botanical Collections 7 Vegetational Studies _~~ ~_~~ ~_~~~~_~__ ~~ 9 Vegetation Map ~~ ~ ~~~ ~ facing 14 Flora 15 Vegetation Areas ~---~~------...:----~----16 Chihuahuan Desert ~ _ 16 1. Creosote-yucca-mesquite _~ _ 17 2. Mesquite-grassland ~----.:.------_.~-- 18 3. Succulent desert ------~----- 20 i Sierra Madre Occidental _~ ~ __ ~ ~_~ _ 20 " 1. Oak-agave-juniper -~~--~:"------~~-~.-":'- 21 2. Pine forest ------.:.------~~------22 Sonoran Desert ~_~ _ 22 1. Colorado, River Delta ------~~--- 22 2. ' Creosote-palo verde-cacti _ 23 3. Sonoran mesquite-grasslands ------24 4. Subtropical mimosaceae-cacti ------24 Sinaloa Tropical _ 25

,Ii I ~,:I' r [ 5 ] ~~' I- J II' ,I

II il 1,1 NOTES TO ACCOMPANY A VEGETATION MAP OF NORTHWEST MEXICO

INTRODUCTION·

I This paper embodies a preliminary study of the vege­ . I tation of northwestern Mexico. Vegetation is here consid­ ered to be the plant cover of an area in its general aspects of dominant associations and formations. The region des­ ignated as northwestern Mexico comprises the Mexican states of Sonora, Sinaloa, Chihuahua, and Durango. These four states contain about 236,000 square miles, or a trifle less than a third of the republic's total area.

BOTANICAL COLLECTIONS The flora of northwestern Mexico has been compara­ tively well studied! The earliest descriptions of plants are to be found in the writings of Tello, Perez de Ribas, Obre­ gon, and Pfefferkorn, and in the "Rudo Ensayo" and the "Relacion de la Nueva Mexico." However, the area was untouched· by trained botanists until the expedition of Charles II of Spain, which worked in Mexico under Dr. Martin Sesse from 1788 to 1804. Moc;ino, Castillo, and Longinos were the members of this expedition who made collections in northwestern Mexico. The chief result of this work was in the information given by Moc;ino to A. P. de Candolle:while the former was a political exile in France. Von Humboldt and Bonpland stimulate'd scientific study in Mexico, but neither of them ever set· foot in the northwest during their visit in 1803-1804. i ,I 1.. The 'chief bibliographies and histories of botanical research in Mexico are: H;emsley, W. B. Biologia Centrali-Americana; Botany 4; 117-137, 316-332, Landon, 1887. Leon, Nicholas. BibliotecC1 Botanico-Mexicama, Mexico, i895~ Harshberger, John. Phytogeographic Survey of North America, 30-33, 82-87, New York, 1911. . . . Standley, P. C. "Trees and Shrubs of Mexico," 9-19. Contributions from the U. S. National He1"barium, Vol. 23, Washington, 1920-1926. Just's Boianischer Jakresbericht. Leipzig, sporadic numbers on "Pflanzen-geo­ graphie der Aussereuropaischen Lander." [ 7 ]

I III , Iii 1, I 1 8] THE UNIVERSITY OF NEW MEXICO VEGETATION OF NORTHWEST MEXICO [ 9

The modern period of research began with Thomas' Shreve. In addition to the plant investigators listed above, Coulter, who explored Sonora in the 1830's and was the there have been several specialists who have visited north­ first collector to send out plant collections from this region. western Mexico while obtaining specimens and data. Among Adolf Wislizenus, in 1846, made the first large collection the best known of these are Trelease for yuccas, agaves, and' in Chihuahua, although Josiah Gregg had collected numer-:­ oaks;, Hitchcock for grasses; Britton for cacti; Shaw for ous .specimens, iIi 'the 1830's, which are chiefly. in the her­ pines; Safford for plants of economic significance; and Stahl barium of the Missouri Botanical Garden, Charles Wright, for cacti and agaves. 1847-1851, made large collections, in Chihuahua and Sonora, which were studied by Gray. In 1849-50, Berthold See­ VEGETATIONAL STUDIES mann, botanist on H. M.'S. Herald, made som'e collections The vegetation of northwestern Mexico has been but im-' in Sinaloa' and' Durango. During the 1850's, various mem: perfectly studied and described, despite the extensivebotan­ bers of the United States-Mexican Boundary Commission; ical investigations in the region.· The wealth of ' floristic especially Schott, Wright, Thurber,Parry, Bigelow, and data has not been synthesized and organized' in terms" of 1 Emory, collected extensively along the border. Guillemin­ I", associations and formations except in a very general man­ Tarayre ..collected for the French Scientific Com)llission in I: ner. Only a few investigators have attempted to describe ii 1865-1866. . , .' . . .' ! ~egime the entire vegetational landscape, including climatic and II The' long: of Diaz was marked by the visits of II,Ii ih~ny edaphic factors involved. These studies have been of small 'noted botanists and naturalists. Among the first, and and scattered areas within the region. ii'I' certainly the great~st field botanist, was Cyrus Pringle, I, In working up this study, use" has been made of I' ~hose Mexican 'collections are unequalled by those' of any ,I published floras, botanical monographs, reports of military, I.' oth'er collecto;. Edward Pah er, whocoIlected mainly' from l1 naval, and boundary commissions, travelogu'es, consular xe-, horthern'Mexico during the, period 1870-1910" ranks second ports, descriptions of landscapes incorporated in geologic o~ly to Pringle. C. V. Hartman and F. D. Lloy? made ex-' reconnaissances, and varied scientific reports which include tensive'collections in Sonora and Chihuahua from 1890 to data on vegetation, e.g., reports of archaeologic, zoologic, 1893' while accompanying Carl Lumholtz on hisarchaeolog1- , ... . and ethnologic surveys. The following paragraphs are cal explorations. ' C. A. Purpus, E. A. Mearns, and ,T. S'. devoted to a consideration of the principal sources utilized. Brandegee gathered many speciinens in the northern por- The vegetation of northwestern Mexico, has been de- I tions of the region. , , scribed in eighteen pages by John Harshberger (Phytogeo~ E. W. Nelson and E. A. Goldman covered most of north­ graphic Survey of North America, 633-6,48,,656-658, New western Mexico while engaged in biological investigations: York, 1911, which appeared in' Die Vegetation' der Erde F. V. Coville and J. N. Rose, curators of the United States series edited by Engler and ,Drude). A map of Nortp National Herbarium, collected extensively in northern Mex­ "1 America, on the scale of 1 :40,000,000, shows northwestern, 1I., :i~ ico. Since the establishment of the Carnegie Desert Labor7 Mexico divided into five vegetational areas: Chihuahuan 'collectin~ ,;j atory at Tucson, Arizona, in 1903, numerous Desert, Sonoran Desert, Western Sierra, Madre, Rocky II' expeditions have been made into Sonora and adjacent areas Mountain, and Jaliscan. Limits of pine, mangrove, and. II ~ I by such botanists as Daniel MacDougal, ,W. A. Cannon, V. II yucca are indicated. In the symposium Naturalist's Guide I,II M. SpaJding, B. E. Livingston, F. E. Clements, and Forrest (edited by V. 'E. Shelford, Baltimore, 1926), '. I: to the Americas I Ii II I:.: I, ":~ ' 10 ] THE UNIVERSITY OF NEW MEXICO VEGETATION OF NORTHWEST MEXICO [11

Shreve and Shelford have an article "Descdptive List of Hayek, August. Allgemeine Pfianzengeographie, 1926. Campbell, D. N. Outline of Plant Geography, 1926. Middle American Biota," 77-80, which briefly outlines nine Hansen, Adolph. Die Pfianzendecke der Erde, 1920. areas for our region: Arid Deciduous Forest (southern Sina­ Hardy, Marcel. The Geography of Plants, 1920. loa), Extreme Desert, Desert, Succulent Desert (all three in Schimper, A. F. W. Plant Geography, 1903. Sonora and Chihuahua, but separated by coniferous for­ Drude, Oscar. Handbuch der Pjianzengeographie, 1890. ests) Dry Grassland (Chihuahua and Durango) j Desert Monographs on families, genera, and species normally Coniferous Forest, Arid Coniferous Forest, Moist Conifer­ stress the floristic rather than vegetational aspects· of the ous Forest, and High Mountain Forest (in the Sierra Madre subject. Nevertheless, valuable data on areal distribution Occidental, progressing from Desert to High Mountain and ecology can be gleaned from many of these works.· De~ Forest with increase in elevation and decrease in latitude.) serving special mention in Die Pflanzenareale series edited This article is illustrated with octavo page map of Mexico by Diels, Samuelsson, Hannig, and Windler, and published and· Central Amedca. The symposium also contains an at Jena since 1926. This serial is 9-evoted to articles and . article on "Natural Areas and Regions of Mexico," 574-596, maps developing the areal distribution of plants.over the by Nelson and Goldman. These writers recognize an Arid earth. The principal monographs consulted are listed below: Lower Tropical division in Sinaloa, Covillea Association Bailey, L. H. Gentes Herbarium, various numbers. in much of Durango, Chihuahua, and coastal Sonora, Pifion­ Bailey, L. H. Standard Cyclopedia of "Horticulture, 1914, iuniper Association flanking the Sierra Madre Occidental various articles. above the Covillea Association, and Pine Association over Baker, J. C. Handbook of the Amaryllideae, 1888. B~rger, -B. Die Agawen, 1915. most of the Sierra Madre Occidental. An octavo page veg­ Britton and Rose. The qenus Cereus and Its Allies in North etation map of Mexico accompanies the above articlf, but it America, 1909. contains several gross errors. This same map was used to Britton and Rose. The Cactaceae, 1920. illustrate "The 'Natural Regions of Mexico," by E. M. San­ Die Pflanzenare-ale: ders in Geographical Review, 11 :212-226, 1921. La Vege­ Shreve, Fouquieraceae, 1931'­ 1899, by Jose Ramirez, contributes little Shreve, Larrea tridentata, 1931. taci6n de Mexico, Shreve, Carnegia gigantea, 1931. of value, as it lacks a vegetation map and is composed Diguet, Leon. Les Cactacees Utiles au Mexique, 1928. mainly of translations from foreign botanists such as G:dse­ Engler, Adolph. Das Pfianzenre(ch, various ~umbers. . bach, Hemsley, and Fournier. Hall, H., and Clemens, F. The North Amencan SpeC'!es of Several plant geographies devote .small sections to Artemisia, Chrysothamus and Atriplex, 1923. Hitchcock, A. S. Mexican Grasses in the U. S. Nat. Mus. northwestern Mexico. .These general works only confuse. Herbarium, 1913. the subject by adding new terms to an already cluttered Karsten, G. and Schenck, H., Vegetationsbilder: terminology, and the maps are on. too small a scale to be of Karsten and Stahl, Mexikanische kakteen, 1903. much practical-value. Among the best of these works are: Karsten, Die Mangrove Vegetation, 1905.- Stahl, Mexikanische Nadelholzer, 1905. Rubel, Eduard. Pfianzengesellschafen der Erde, 1930, with a Stahl N ordmexikanische Xerophyten, 1905. map by H. Brockmann-Jerosch. purp~s Arizona Wustengebiet, 1907. Graebner, Paul.- Lehrbuch der allgemeinen Pfianzengeo­ Missouri B~tanical Garden, Annual Reports, vols. 3, 4, 7, 12, graphie, 1929. 13, 18, and 22. Various articles on A~aves, Yucceae, Braun-Blanquet, J. Pfian~enso;iologie,1928. Y~glandaceae by Trelease, Mulford, and RIley. 1

12 ] THE UNIVERSITY ,OF NEW MEXICO, VEGETATION 'OF NORTHWEST ~MEX'ICO [ 13

New York Botanical Garden, North America Fl01"li, various Aldous,A., and Shantz, H. "Types of Vegetation' ih ,the numbers. Semi-arid Portion of the U: s. lour, Agric;, Rese,arch Shaw, G. R. The Pines of Mexico, 1909. 28: 99-128, 1924. , Shreve, Forrest. The Cactus and Us Home. Bailey, y. Biological,Survey of Texas, 1905. ", Standley, Paul. Trees and Shrub's of Mex1:co, 1920-1926. Bailey, V. Life Zones and Crop Zones of New Mexico, 1913.' Trelease, William, Genus Quercus, Mem, Nat. Acad. Sci. 20, Bowman, Isaiah. Forest Physiography, 1911. 1924. Bray, W. L. Distribution and Adaptation of the' Vegeta~ Trelease, William. "The Yucceae," Missouri Botanical Garden, tion of Texas; 1906. ' , Thirteenth Report, 1902. Bray, W. L. Vegetation of the Sotol Country in Texas, 1905. Considerable information was derived from articles Clements, F. C. Plant Indicators, 1920. on the economically valuable plants of Mexico. Among the Coulter, J. Botany of Western Texas, 1891-1894. " leading. works and authors are : Griffiths, D. Native Pasture Grasses of the U. S., 1915. Livingston, B." and Shreve, F. The Distribution of Vegeta- Conzatti; Casiano. Los Generos Vegetales Mexicanos, 1903. tion in the United States, as Related to Climatic Con~ 9ook, 0: F. Numerous articles, especially on tropical food­ ditions, 1921. stuffs. MacDougal, D. T. The Salton Sea; 1914. ,Cordero, y Seguro. Reseiia sabre el cultivo' de algunas plantas Mearns, E. A. Mammals of the Mexican Boundary of the industriales, 1884. U. S., 1907., Diguet, Leon. Numerous articles, chiefly on cacti. Meinzer, E. O. Plants as Indicators of Ground Water, 1927. Dodge, C. A descriptive ca,t~logue of useful fiber plants of Merriam, C. H, Life Zones and Crop Zones, 1898. the world, 1897. Lloyd, F. E. Guayule, a Rubber Plant of the ChihuahWt Des­ Newberry, J. S. "Flora of the Country Bordering the Rio ert, 1911. Grande in Chihuahua and Texas," in Bulletin. Torrey Martinez, 'Maximino. Las' Plantas Mas Utiles de la Repubc Botanical Club, vol., 10. lica Mexicana, 1928. Pellett, F. C. American Honey Plants~ 19~!3.,' Martinez, Maximino. Plantas Narcoticas de Mexico, 1925. Sampson, A. W. Native American Forage Plants, 1924. Materia Medica Mexicana, 1900, various articles. Shantz, H., and Piemeisel, "Indicator Significance of the Noriega, J. M. Contribucion al Estudio de la Gobernadora, Natural Vegetation of the Southwestern Desert Region," 1923. Jour. Agric.- Research, 28:721-801, 1924; Noriega, J. M. Historia'de Drogas, 1902. Shants, H., 'and Zon, R. Atlas of American Agriculture: Noriega, J. M. Las Plantas Mexicanas y Algunas Exoticas Nat~tral Vegetation, 1924. Productoras de Materias Colorantes, 1919. ShreVe, Forrest. "A Map of 'the Vegetation, of the United Nueva Farmacopea Mexicana, 1904, 4th edition, various States," in, Geographical Review, 3:119-125, 1917. articles. , Shreve, F. The Vegetation of a Desert Mountain Range as Ramirez; Jose: Sinonimia Vulgar y Cientifica de las Planta~ Conditioned by Climatic Factors, 1915. Mexicanas, 1902. ' Spalding, V. M. Distributio,n and Movement of Desert Plants, 'Record, Samuel. Timbers of Tropical America, 1924, 1909. o Rose, J. N. Notes on Useful Plants of Mexico, 1901. Thornber, j. J. The Grazing Ranges of Arizona, 1910. Safford, W. E. 'Numerous articles, especially on drugs. Torrey, John. Botany of the U. S. and Mex.Boundary, 1859, Because of the contiguity of' Arizona, NewMexico, and Wooton, E. and Standley, P. The Flora of New 'Mexico, 1915. ,Texas to portions of northwestern Mexico; it was possible to The data on individual areas in north~estern Mexico ~' use number of 'excellent'studies prepared on the American were derived mainly from,scientific reports and travelogues areas'. The most important of these studies are: • , ••,. I having vegetational data only incidentally. These data were '-,0_._UP (i'~...~-----

14 ] THE UNIVERSITY OF NEW MEXICO j' ..------,._--- It -~~- synthesized, co-ordinated, corrected, and interpreted in the r-. -- light of personal observations which were most extensive I in Sinaloa, northern Sonora, and northern Chihuahua. The following list includes most of the works utilized:

Audribon, J. W. Illustrated notes, 1852. Bell, P. L. Mexican West Coast, 1923. Drude; O. "Das Sonorische Florenreich" in Ber. der Freien Verein. f. Pfianzengeographie u. Systemat. Bot., Jahre i--. _ 1920 u. 1921, 1922: (J Hemsley, W. B: Biologia Centrali-Americana': Botany, vols. 1-5, 1879-1889. Hornaday, William. ·Camp-fires on Desert and Lava, 1908. Hovey, E. C. "The Western Sierra -Madre of Chihuahua," in Bull. Amer. Geog. Soc.,·37:531-43, 1905. Howarth, O. H. "The Western Sierra Madre of Mexico," in Geog. Jour. 6 :422-437, 1895. Huntington, Ellsworth. The Climatic Factor as IllUstrated in Arid America, 1914. I Lumholtz, Carl. New Trails in Mexico, 1912. '1 w,l ~y:: 1.,0",:;) Lumholtz, Carl. Unknown Mexico, 1905. MacDougal, D. T. "Across Papagueria," in' Bull. Amer. Geog: Soc., Yol. 40:705-725, 1908. ' MacDougal, D. Td Botanical Features. of North American ·1 ,.,..·· "':~(,.~~..J Deserts, 1908. . I ,-'. 0 MacDougal; D. T. "Delta and Desert Vegetation," in Botan­ I ical Gazette, 38 :44-63, 1904. 'McGee, W. J. The Seri Indians, 1895-1896. Ortega, J. G. "Exploracion Biologica por la Cuenca del Rio .Tamazula," in Mem. y Rev., Soc. "Ant. Alz.," 47 :145-153, -"'.' . 1927. . . :,; ,..\ Pringle, C. C. "Forest Vegetation of North Mexico;" in .'- '\ - Garden and Forest, '1:70, 105, 117, 141" 226, 238, 429, ;: ,. ...~.;i.. ;' .. 441; 1888. I ....~~ ," '.::> Seemann, B. "Flora of Northwestern Mexico," in Botany of the VOy(J,ge of the H. M. S. Herald, pp. 255-346, 1852- o 1857. . Shreve, F. "Deserts of Northwestern Sonora,'.' in Carnegie Inst. Yearbook, 23 :138-140, 1924. .,-.. Waibel, .L. "Die Nordwestlichen Kustenstaaten .Mexikos," , - in Ge"og. Zeit, Leipzig, 33 :561-567, 1927: I .. .",'f .•&,.""" /;.:' ~ Wallace,Dillon. Beyond the Mexic(J,n Sierras, 1910. f~\'(~:~'~J .j ~J { I ')1,'11.<" • ~;. ;[; : I~(> r :r;.~:'.:,·~.h '\, 'h~'" ~ • ~-.: roC: "'". ;..- ..~t., ,:i ..., "~7'\'"'' f

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VEGETATION, OF NORTHWeSTERN M£~Co dl

'I" j, " Ve9sttltion' A,eAs Floristic 80u.·~JJo,.ies 'If. 'If CJ·II/'u.cl../olcn Desert: , 'I~r, ,. C,.eosote~l"cco~", eS9"ite ••.,.•._, r ::zxn Norl"e"~IVimit of 1. MUIJuiie-'''''',sl,.f1 d ...... ••..•••ll 3. 5v.cc", lent Desfl'*- """" 111 Ina "9"o~~1 . ' -th ,f S;~,.,.a OeciJe~tQ/: -S au we$/ern '''''it 'MaJ,.e of c"'eoso~'e bush a 1 ,. O"k- Jave'J"'f1'!e'""" .-•..••. :a ~ ','/,1 2· Pifle fo,.est .... ".••••• _ "'" y ~ '! (...... ( 50"0,.0.11 Dese,.t: ~·(v' l ,~ -- BOUndary ~f ,vegeffffion .~ <-" ..... I. Co/o,.oJo Dalla ASSClC/Cltioll ••• •• X . 2, Creo$ote~pa./~'IfI,.de·CQcti • •.••.m district r,',"\l , '->'i./,., '3' Sanoron mes1uite",.osslollJ_...YI1l NOTE' The 01,,,. bonn"ri"I 'j i-.JI }, ; J 4 Su.btrofit:a.1 m ,m OSQeoe~ coct•.n: of vegetation districts; indicated in the southern and eastern por- ..+_,] ; S'naloo TI-opica/: repie~ent (/~-=? l, 5erni'a"j'd scl-ub_ X tions of the map, lack _\ Z·Humia scrub .•...... ••...• xr: 'htUdynn.n't"tull~ /;;\' '~:.,

---'--'------~--~------::----~~----L---.1--~~~·-..l:·~2'-I, '\ ~---.J.,,/' ,.',"; ------VEGETATION OF NORTHWEST MEXICO [ 15

.~~ FLORA ,v .u . The flora of northwestern Mexico is quite diversified, ! ! as would naturally be expected in a region situated on both sides of a tropic (22°N.-33°N.), and extending from a coast line nearly a thousand miles long to the crests of a mountain range which average over 8,000 feet in elevation. High continental-interior and coastal deserts, merge into i " "'.-; .' ' grassy steppes and shrub savannahs, which are succeeded , ...' '0' .. I ,by upland' coniferous and lowland tropical forests. With .'>I . / " great extremes and ranges of temperature and precipitation

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16 ] THE UNIVERSITY OF NEW MEXICO T VEGETATION OF ' NORTHWEST' MEXICO [17

':; and cacti are found far north into the Dakotas and Wyom­ 'Durango. This elevated (3,000-7,000 feet) Basin and Range , ,II ing; and it is a matter of present observation that Acacias country falls into the arid climates (BWh and BSh of Koep­ 'I, "'i" and mesquites (Prosopis) are steadily taking over formerly pen) due to low precipitation values, as the mean annual . ',:' i.1I I, en~ q grass-covered areas in Texas. Tropical vegetation has temperatures run under 20°C., excepting in the extreme ,I ,I tered northwestern Mexico along the Pacific coa~tal plain' northeastern portion. Xerophytic ~ucculents (cacti, No­ II where it attains to northern Sinaloa. The mangrove (Rhiz~ ,I) linas, Dasylirions, Yuccas), microphyls (Prosopis, Larrea, ophora mangle) extends along the strand into southern Fouquiera, Acacia) and steppe grasses (Sporobolus, Boute­ Sonora. From the above it can be seen that northwestern loua, Aristida, Hilaria, Munroa) form the bulk of the vege­ Mexico constitutes a primary Xerophytic vegetation unit tation. In the more humid isolated mountain areas, oaks, which has been modified and augmented by tropical, north­ junipers, and pines dominate the landscape. Along the ern mountain, and prairie invasions. The identity of this river courses are gallery forests made up of cottonwood north,Mexican vegetation region has been recognized by such phytogeographers as Seeman, Hemsley, and Harsh- (Populus sp.), willows (Salix sp.), walnuts '(Juglans sp.), berger. ' hackberry (Celtis sp.), ash (Fraxinus sp.), and sycamore' VEGETATION AREAS (Platanus sp.), in addition to thickets of Prosopis, Mimosa, Acacia, and other Legum~nosae. , On the basis of intrusive and ~ative floras: modified by 1. Creosote-yucca-mesquite: This area falls into three local climatic and edaphic factors, northwestern Mexico falls subdivisions or vegetation districts. In northern Chihua­ into four major vegetation areas, each susceptible to ,sub­ hua, from ,the mesa fronting the Rio Grande west to Laguna division. These major divisions are expressions of latitude, Guzman and the Santa Maria River and from the Potrillo continental position, a~d elevation in so far as these ifems Hills north of the International Boundary south to Bajio del condition temperature and' precipitation. The Chihuahuan Ojo Caliente, Laguna Patos I;tnd the Conchos'basin, is a Desert area embraces the most continental'interior portions .gravel- and sand-covered plain scantily vegetated with of the elevated tableland that makes up Chihuahua and yuccas (mainly Yucca elata), creosote bush (Larrea triden~ .Durango. The Sonoran Desert area comprises. the extra tata), and mesquite (Prosopis julifiora). The creosote bush tropical high pressure lpwland parts of Sonora and northern is the dominant plant of this creosote-yucca-mesquite asso- . Sinaloa, which are somewhat in the rain shadow of Lower ciation; Hundreds of square miles of arid basin land California's Peninsular Range. Betwee,n th'ese arid areas present to view the drab green of creosote bushes widely is the, Sierra Madre Occidental area, with a~egetationtypi­ spaced over the gravelly plains. The yuccas, mesquite, and cal of humid mesothermal highlands. The Sinaloa Tropical Koeberlinia spinosa are common in the sand dune areas area coincides with the northern extension of the PaCific where they often have contributed to the formation of the coast tropical forest and is characterized by a deciduous dunes. Occasional Crotons, chamiso (Atriplex' canescens) thorn shrub and forest. ',. and Zizyphus flank the dunes. On rocky ridges and the Chihuah'uan Desert: The Chihuahua Desert area com­ small isolated ranges Agaves, ocotillo ,(Fouquiera splen­ prises eastern and northern Chihuahua arid eastern' dens), No linas, Dasylirions, cacti, Yuccas, and mesquite vie 2.. The botanical nomenclature here used conforlns as closely as possible with the with the ubiquitous creosote bush. '. Gramas (Bouteloua)" usage m Paul Standley: "Trees, and Shrubs of Mexico," U. S. Nat. Herb:. Cont. vol. 23 1920-26. . ' ,-' needle-grasses (Aristida) and tobosagrass (Hilaria ,mutica)

• 18 ] THE UNIVERSITY OF NEW MEXICO VEGETATION OF NORTHWEST MEXICO [ 19

form the scanty grass vegetation. This district is one of the where their expanse may be broken only by popotillo truest deserts in northern Mexico, the annual precipitation (Ephedra sp.), a few'yuccas, an occasional opuntia Or oco­ averaging less than 200 mm. tillo, and some mesquite and hojasen. Tobosa grass grows 2; Mesquite-gral?sland: West and south of the above mainly in areas of fine textured soils, and the bunch grasses described district is a higher, somewhat less arid region of are found over areas normally subject to annual flooding. steppe climate whose vegetation is of a type transitional be­ Various grasses vegetate the borders of the barren playas, tween desert shrub and mesothermal woodland. Grasses, the dominant species being salt gras~es (Distichlis spicata, mesquite, creosote bush, and hojasen (Flourensia sp.) dom­ and Eragrostis obtusijiora) , and alkali sacaton (Sporobo­ inate the landscape. Mesquite supplants the creosote bush lusairoides). The edges of the flooded areas usually mark as the dominant member of the vegetation; and the latter is the inner limits of the grassy zone, although in some places restricted to high benches, outwash fans, and upper pedi­ clumps Qf sacaton extend well out into the flats. "[ ment slopes where the soil is coarse textured, permeable, The banks of the larger streams often carry a consid­ , iill and well drained. The .mesquite attains its best growth in erable tree vegetation consisting of cottonwood, willow, the lowland areas of fine textured soils and high water table, sycamore, walnut, hackberry, ash, and alder. The Fremont ',,i'I'jill but also extends up washes and onto areas quite deficient in cottonwood (Populus fremontii=wislizeni) is the outstand:' water supply. In some of the better watered valleys thick­ ing member of the gallery forest. Walnuts (Juglans rupes­ :,11 \ ets of' arborescent' mesquite, frequently associated with , , tris, and J. major), desert willow (Chilopsis linearis), and I: screw bean (Prosopis pUb'escens) , Acacias, Koeberlinia, hackberry (Celtis reticulata) also occur singly and in small "'Iill' chamiso, and Mimosas,. occupy the river plains. Hojasen groves and clumps along the arroyos. Occasional oaks and (Flourensia cernua) ranks only after mesquite and creosote, junipers fringe'the upper margins of the western basins, I I I ',',II I among the shrubs. It usually occurs on lower'slopes, mixed and mark the change to the Sierra Madre Occidental area or 1 "1 with mesquite and creosote. . The sequence of the shrub to the higher mountain ranges of the district. These desert : :[1 1 association is quite marked where slopes are well developed. apd steppe ranges have a vertical succession from mesquite­ I '.I! I fol~ I 'll.· Mesquite normally occupies the middle of the valleys, grass-creosote, through juniper, agave, and oak, to pines "i:~~i lowed by a .mixture of mesquite and hojasen in which -in the case of the highest ranges. Oaks are dominant, hojasen becomes more and more abundant until creosote Quercus emoryi prevailing on the lower slopes and Quercus : I ,:, j' I bush appears as the marked slope begins. The creosote bush grisea on the upper slopes. In the steppe lands of the Son­ 1:1· increases rapidly, and is nearly pure on the upper slopes and oran Desert area, there is an association quite similar in i I ridges. general to that of the Chihuahua mesquite-grassland, but 'il Grasses are well developed throughout, and great ex­ there are sufficient floristic differences to justify a distinc­ ","'1 panses of grass country are frequent in the western basins tion. between 4,000 and 5,000 feet elevation. The chief grasses Along the Rio Gr.ande and lower Conchos valley in Chi..; are the 'gramas, various needle grasses, curly mesquite huahua, the vegetation resembles that of the larger river (Hilaria belangeri), tobosa grass (Hilammu,tica), several , valleys in the steppe country. There is, however, an increase bunch grasses (Sporobo[us~, and false buffalo grass (Mun­ in the Acacias and Mimosas so typical of the lower Rio roa squarrosa). Black grama, curly mesquite, and false Grande. This gallery vegetation is more scrubby thanar­ buffaJo grass predominate on the upper, well-drained slopes, boreal. It has been mapped as an extension of the mesquite-

I, II • Ii ..

20 ] THE UNIVERSITY OF NEW MEXICO VEGETATION OF NORTHWEST MEXICO [ 21 .J " I grassland district, as mesquite is still dominant, and most of this vegetation area coincides fairly well with the areas of I 'I the associated plants are typical. A somewhat similar mesothermal savannah' climate (Cw of Koeppen). Two I' I extension of mesquite-grassland is found along the lower associations are dominant in this forest area which extends hll Nazas into the Coahuilan sink. south for 800 miles, and averages 50 to 100 miles in wi,dth. I' III I 3. Succulent desert: Southward from the Conchos 1. Oak-agave-juniper: Commencing, at an elevation ,) I and the Big Bend of the Rio Grande there is a marked in­ of around 5,000 feet in the north, and somewhat higher in 'I' crease in the number of species and individuals of succulent the south, the mesquite, creosote-bush, popotillo, and other hll '!II and semi-succulent plants. Cacti, Agaves, Nolinas, Dasy­ shrubs that dot the basin grasslands are· supplanted, by ,',f lirions, and Yuccas are dominant members of the vegetation, Agaves, juni'pers, and oaks. The Yuccas, Nolinas, Dasyli­

" along with various. Leguminoseae, creosote bush, and oco­ rions, and Opuntias continue upward for another thousand I' tillo. Along the washes grow mesquite, Acacias, Mimosas, :j'eet in this park landscape of mesothermal climate. Gramas Faroselas, hackberries, Lyciums, and Condalias. Creosote ~ontinue to be the dominant grasses. Between 5,000 and bush dominates most of the district, but yields to the succu-: 6,000 feet junipers, ,oaks, and Agaves prevail. From 6,000 lents on the slopes and ridges. The grass vegetation is to 7,000 feet, there is a pine-oak tral}sition belt" and above poorer than in the creosote-yucca-mesquite association. Both 7,000 feet is the pine country. The succession is from juni­ capsular and baccate yuccas are common. Cacti increase in. per through oak to pine, with varying proportions of these size and numbers southward, and include numerous Echino­ trees and their associates: Neither soil nor slope seems to cacti, Mamillarias (Neolloydia), members of the Cereus condition the vegetation as much as does mere elevation. group, et~.• in addition to the Opuntias found to the north. Oaks are dominant in this foothill formation, QUercus Agaves, especially lechuguilla, Nolinas (bear grass), and emoryi (black live oak) prevailing at the lower elevations, Dasylirions (sotol) have such a development that this dis.., and Quercus grisea (gray live oak) making up nine-tenths trict is sometimes referred to as· the sotol, or lechuguilla of the oak vegetation in the upper elevations-mainly above country. Two species of ocotillo are important items in the 6,700 feet. On the Pacific coast side Quercus oblongijolia landscape. The richness of this district in succulents,prob­ (white live oak) and Quercus Arizonicus (Arizona gray ilbly e~presses a close r~lationship to the cradle of such arid' live oak) are dominant. Several other species of oaks, how­ climate plants more than any special suitability of climatic ever, are represented in this formation, which varies, in or edaphic factors. appearance, from chapparal through oak savannah to· Sierra Madre Occidental: The Sierra Madre Occidental forest. Junipers (Juniperus pachyphloea. and J. Mex­ area comprises the western highland margins of the Mex.:. icana) grow on the sunnier slopes and somewhat dry ridges; ican central plateau or tableland, with elevations between singly or inquite' open groves, commonlyinterspersed with 5,000 and 10,000 feet.· The precipitation 'values run from oaks arid Agaves. The Agaves grow singly throughout the 500 mm. to over 1,200 mm., with mean annual temperatures association area. .. under 18°C. The annual rainfall, although concentrated in On the Sonoran 'slopes,the lower transition zone from the summer months, is sufficient to maintain a mixeddeci- basin grassland to oak-agave-juniper contains relatively \ duous-coniferous woodland at the lower elevations and a f~w Yuccas, Nolinas, Q,nd Dasylirions, while Parkinsonia, fairly pure, open coniferous forest higher tip. Iil. general, J1:cacia, Prosopis, and Pouquiera are well represented, The

I, ,111 ! 'I I' II: I' ,I, I Iii .II I',

22 ] THE UNIVERSITY OF NEW MEXICO VEGETATION OF NORTHWEST MEXICO [ 23" I I ~ inferior limit of oaks is considerably lower than on the Chi­ bean, A triplex, and Typha along the distributaries and huahuan side, as oaks are common at elevations under 3,000 sloughs. The mud flats are covered with salt grass (Dis~ feet. In Sinaloa the transition from tropical to mesothermal tichlis. sp.), arrow weed (Plucnea sp.), wild rice, wild hemp, I'" vegetation is marked by the complete absence of Yuccas, and quelite, with scattered clumps of mesquite and, other Nolinas, Dasylirions, ocotillo, and creosote~bush, and only a shrubs. The tangle of vegetation is quite bewildering and scanty representation of mesquite. These succulents and nearly impassible over large areas. ' shrubs are replaced by a great number of Mimosas, Acacias, 2. Creosote-palo verde-cacti: The northwestern por­ Cassias, Caesalpinias, figs, laurels, and other plants typical tion of Sonora is probably Mexico's region of least precipi­ of the Sinaloa tJ;opics. The transition zone in Sinaloa com­ tation, many of the annual values averaging under 50 mm. mences around 3,500 feet elevation, which is about the lower This district extends from a sand dune and salt flat seacoast limit of oaks. ' up to about 2,500 feet, but most .of it is under 1,500 feet 2. Pine Forest: The district of pine dominion is on elevation. Creosote bush, paloverde (Cercidium torreyana, the plateau and mountain tops above 7,000 feet. Most of the and Parkinsonia microphylla), Opuntias, mesquite, Acacias, r forest consists of Pinus Arizonica, Pinus ponderosa, and Franf!enas, palo fierro (Olneya tesotaj, and the Cereus Pinus montezum,ae~thefirst two dominating the north, and gigantea dominate the landsc'ape of this truly arid district: the Montezuma pine prevailing in Durango. Mixed with Galleta grass (Hilaria sp:) is distributed, sparsely through­ these three species are individuals of Douglas fir (Pseudot­ out. , The vegetation is typically Mexican,_although it ex­ suga mucronata); Pinus lumholtzii, Pinus chihuah~lana, tends' northward into, Arizona. There has been influence Pinus refiexa, Pinus ayacahuite, etc. The Arizona pine and across the Gulf from Baja California, and in the south from western yellow pine (Pinus ponderosa) are commercially the tropical association. ' : ' most important. The growth is open, although there is some On the coarse gravelly mesas the characteristic plants undergrowth of Ceanothus, Arctostaphylos, and Arbutus. ~re creosote bush, palo verde, palo fierro, saguaro (Cereus=' Pinus cembroides and Pinus edulis (pinons) occupy the Carnegia gigantea) , cholla (Opuntia sp,), ocotillo, and warmest and most arid slopes of meager soil. The grass Acacias. The creosote bush extends to the coast,where it is cover is fairly good throughout the forest. Numerous moun­ associated with chamiso and galleta grass on the plains tain meadows also occur. The canyons' carry species, espe­ back of the beaches, and with Ephedra in the dune country. cially the scrubby forms, representative of the entire area. Cacti seldom attain to the coast except in'the southern porr tion where saguaro, pitahaya (Lemaireocereus thurberi) Sonoran Desert: The Sonoran D~sert area possesses and other column'ar cacti are present. The two cactfnamed four association districts, in addition to the scattered high;, are commonly associated together and with ocotillo and palo land regions having a vegetation of the Sierra Madre Occi­ verde on southern slopes and' outwash fans. On many of dental oak-agave~junipertype. These ass.oci.ations express the desert plains there are nearly pure stands of cholla cac­ changes in temperature and water supply a,s conditioned by tus, especially northwest of Altar towards the Pinacate elevation, river flood plains, and.latitude. country. ,The mountains and ridges of the arid district carry 1. Colorado River Deita: The alluvial soil of the hot, " a scanty vegetation of ocotillo, cholla, and columnar cacti, I, nearly rainless Colorado River delta carries a: rather dense II: and some Yucca, Notina, and Dasylirions in the northeast­ I vegetation of willow, cottonwood, Pluchea, mesquite, screw ern portion. ' ". , , 'I'

I'! 1,1 I, . 'II "'!' :" (I·a-- ',,' 'I,'i "',1'1, !.I' ,\. I','It 11 r"70 :,1 I ',:,' ",,:1' :'\ , ' , I I.:i I. 'I " '" II THE UNIVERSITY OF NEW MEXICO VEGETATION OF NORTHWEST MEXICO [ 25 ~,; 24 ] I :1 , " ',' On the flood plains and alluvial areas, there are large southern river valleys higueras (Ficus sp.), huanacastles trees of Parkinsonia, Olneya,Prosopis, and Acacia, inter­ .(Enterolobium), sabinos (Taxodium sp.), and other tropical , ";[j trees are increasingly numerous~ "I ';,hi" mingled with columnar cacti, smaller cacti, chamiso, Fran­ ,! ,,1 'I: 1,1 seria, and galleta grass. In the arroyos and washes a vege­ Sinaloa Tropical: The Sinaloa tropical district'is tropi­ ", I , ':, 'Ii, , tation of mesquite, catsclaw (Acacia sp.), palo verde, palo cal in temperature values, but varies in moisture supply be­ I,':i fierro, creosote bush, hackberry, Ephedra, Condalia, and tween ,savannah and desert conditions. Four associations, , "i!!" ocotillo prevails. Along the southern coast there are heavy ,"" '\ are prominent in this district, agreeing in distribution with :,!I, III" stands of Pachycereus, and cirio (Idria columnaris). Along the c'oastallagoons, river flood plains, coastal inter-fluviatile ! I!:! I, the southern foothills are numerous palo blanco trees uplands, and foothills of the Sierra Madre Occidental. Due , (Ipomea arborescens), intruders from the tropical area. to difficulties in mapping on a small scale map these forma­ 3. Sonoran mesquite-grasslands:' The northern and tions -have not been differentiated on the vegetation map. eastern basins and plains of Sonora carry a steppe shrub Approximately between the Piastla and Quelite rivers there vegetation quite similar to that of the Chihuahuan mesquite,. is a change from semi-arid to humid conditions with over 750 grassland. The disti~ctive features of the Sonoran district mm. of precipitation annually. This change is marked by' are dominance 'of grama ,grasses, numerous cacti, relative a taller and more closely spaced vegetation which attai;ns unimportance of Yuccas, creosote bush, Flourensia, Ephedra, to almost forest proportions in many of the river valleys. COndalia, and Koeberlinia, lesser importance of mesquite as This, however, is more of a change in formation than in a dominant, and the presence of Parkinsonia and Franseria. association.. The arboreal constituents of the gallery forests are nearly Along the coast, especially on the mud flats bordering the same in both districts, but there is a stronger develop­ lagoons, there is a dense shrub vegetation. This vegetation ment of oaks and Acacias in' the'Sonoran district. Palms consists of mangrove (Rhizaphora mangle) in the .. tidal are common in many of the western canyons, the chief areas, and seagrape (Coccoloba twife~a), Pisonea sp., mora genera represe~ted being Washingtonia, F)rythea" and (Chlorophora tinctoria) , numer.ous Caesalpinias, etc.,alo:pg Inodes. the shore. Various palms, especially Cocos nucifera are 4. Subtropical mimosaceae-cacti: Covering the arid common near the beach. Dense and nearly continuous scrub coastal and river valley portion of southern Sonora" and forests of this coastal association occur south of Mazatlan, particularly from' the mouth of the Rio del Presidio south­ " northern Sinaloa is a spiny shrub and cacti formation domi­ ,iii nated by Mimosaceae and columnar cacti. Creospte bush; ward. North of Mazatlan the association is more open,' saguaro, and Fouquiera splendens Of the northern districts lower, and separated by long stretches of sandy beach. are virtually lacking, their places being taken by numerous The flood piains of the Sinaloa rivers and 'adjacent up­ Caesalpinins, Cnssins, Mimosas, and palo santo (Guaiacum land slopes have been cleared and cultivated for many cen­ coulteri). This vegetation is riot distributed uniformly, but turies, in parts going backeven to pre-Spanish days, accord­ is arranged in clumps, gathering into a nearly continuous ingto the evidence of archaeologic sites from the Culiacan cover in wetter spots. Various Mimosaceae and columnar river southward~ The portions not cleared for cultivation cacti especially form large stands which extend for miles, as have been selectively devegetated in accordance with de­ in the deltas of the Yaqui, Mayo, and Fuerte riv:ers... In the mands for charcoal, timber, cabinet woods, and dye woods. .~ i . 1·'·l·1 ".'.·.·.·.1I , 1"1 ''I I"~'ii, "1,.11",1 ,III!' ' VEGETATION OF NORTHWEST MEXICO [ 27 26 ] THE UNIVERSITY OF NEW MEXICO "II giant bald cypress or sabino, Taxodium mucronata. Other I Where formerly cleared areas have gone back into the wild; important families are Lignum vitae (Guaiacum sp~, known 1'/: the secondary vegetation has an apparently greater devel­ as palo santo and guayacan), Rutaceae (Casimiroa edulis, ]"'III[ opment of scrub than was originally the case. Through0.ut 'I' 'I the sapote), Burseraceae (Elaphrium sp., copal) , Meliaceae "I,/!I the district the native associations have. been altered con­ (Swietenia sp., caoba), Euphorbiaceae (Euphorbia sp., siderably, so that now. there are large areas carrying an un­ I"ii·I';·'I·"·:'I' Croton sp., Jatropha sp., Sapium sp., etc.), Rhamnaceae "'I' 'I naturally large percentage of commercially worthless trees 11 and shrubs. From these preIiminaryremarks it is evident (Zizyphys, Condalia, Karwinskia, and Ceanothus), Bom­ 1.'/ ; "I'" that the present vegetation of Sinaloa cannot be considered bacaceae (Ceiba sp., pochote), and Convolvulaceae (Ipomea arborescens, palo blanco). " "natural." Generalizations as to dominant floristic categories, The higueras, huanacaxtle,' and sabino are often trees however, can be made with considerable accuracy. The over a hundred feet high with an imposing spread of foliage. Leguininoseae form the' dominant order. The Minwsa, These trees, together with mora, ebano, brasil, and guamu­ r Senna (Caesalpinaceae) and bean (Fabaceae) families have chil, are the most noteworthy species of the river valleys. probably more than a quarter of the total tree and shrub Many of the trees and shrubs carry'epiphytes and parasites. species of the area, and contribute possibly three-quarters On the slopes and foothills, palo blanco, Agaves, pochote, of the individuals making up the vegetational landscape. and cardon (Pachycereus) punctuate the monotony of the Among the leading Mimosa genera are Prosopis (mesquite)', spiny "monte" scrub. These species become lost in the inc~eased Mimosa, Acacia (commonly known as husiaches), Callian­ higher "monte" developed towards the south by dra Enterolobium (huanacaxtle), Inga, and Pithecollobium precipitation. Towards the Sierra Madre Occidental, the (g~amuchil, chino, una de gato, etc.). The Senna family tropical association first loses the higueras, mora, huana­ includes such genera as Cassia' (most of the' species known caxtle, and sabino, replacing them with oaks, laurels, wild as biches), Bi'LUhinia, Haematoxylum (brasil); Caesalpinia plums and other plants of the transition tomesothermal (ebano, "dividivi," palo colorado, i"guano, tabachin, etc.), climatic conditions. Tropical vegetation, however, advances Parkinsonia and Cercidium (palo verde). The numerous far into the Sierra Madre along the deep barrancas that f~baceous genera include Indigofera (anil) , Gliricidia, carry low elevations for many miles back of the coastal Parosela and.Nissolia. These legumes, together with vari­ plain. . ous cacti, chiefly columnar, dominate the inter-fluv~atile areas and extend from hilltop to valley bottom. The "monte" , thus formed is a: dull green wilderriessdifficult to penetrate excepting along cut trails. . In addition to the legumes, the river flood plains carry a considerable arboreal vegetation whose leading members represent a number of genera and families. The mulberry family contributes Chlorophora tinctoria (the mora, or fus­ I' tic of commerce), nearly a dozen species of Ficus (higuera, I nacapuIi, matapalo, sabali, tescalama, etc.), and the Cas­ tilla elastica (hule). The pine family is.represented by the

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