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Trees of the Northern Sierra Madre Occidental
and Sky Islands of Southwestern North America
Richard S. Felger1 and Matthew B. Johnson
2
Abstract.-This report covers the naturally occurring montane tree flora of the
northern Sierra Madre Occidental of eastern Sonora and western Chihuahua and
the sky islands extending into southeastern Arizona and southwestern New
Mexico. This flora is comprised of 233 species in 130 genera and 61 families,
which represents approximately 5 percent of the total flora of the region. The
region is a meeting place of the temperate North American and Neotropical tree
floras with intrusions of Sonoran and Chihuahuan desert at lower elevations. The
legume (Fabaceae), oak (Fagaceae), and pine (Pinaceae) families are the most
diverse, and the oaks (Quercus) and pines (Pinus) are the largest genera. This
is the first comprehensive listing of the trees of the northern Sierra Madre
Occidental. Extensive areas of tropical deciduous forest (TDF) cover the lower
elevations of the southern part of the region in Sonora and Chihuahua and harbor
60 percent of the regional tree flora. Oak woodland and pine-oak woodland occur
at higher elevations and mixed conifer forest at the highest elevations, and
support 43, 33, and 11 percent respectively of the regional tree flora, The Madrean
forest once stretched unbroken into the American tropics but accelerating
deforestation is leading to fragmentation of the keystone species populations,
INTRODUCTION
We are including all of the tree species known
to us in the montane regions at elevations above
the deserts and grassland in the north, and above
tropical thornscrub in the south. The northern sky
islands, especially at higher elevations, have a
continental and temperate makeup. Many north
temperate tree species penetrate far southward in
the interior of Mexico at intermediate or higher
elevations in areas such as the Central Plateau.
Fourteen percent of the tree flora, or 33 tree taxa
(species and a few subspecies or varieties) reach
their southern limits in the region (Table 1, p. 7883).
Overall, the region is arid to semi-arid except
at the highest elevations. The lower elevations in
the northern part of the region are bounded by the
Sonoran Desert on the western flanks and the Chihuahuan Desert and grassland on the eastern
flanks. The southern mountains, especially at
lower and intermediate elevations, support tropical and subtropical biota. This southern flora, in
southeastern Sonora and southwestern Chihuahua, consists largely of a flora that is continuous
with the American tropics. As one moves northward through our region, there is a tendency
towards a reduction in stature and an attrition of
tropical species and genera. Seventy-two percent
This publication covers the trees of the sky island mountains of southeastern~rizona,
southwestern New Mexico, northeastern Sonora,
and northwestern Chihuahua, and the contiguous
northern Sierra Madre Occidental in western Chihuahua and eastern Sonora. The northern limit of
this bioregion is mar ked by the Pinalefto Mountains (Mt. Graham) in Arizona. Out of practicality
we have set the southern limit of this study at the
Sonora-Sinaloa border and adjacent mountains of
southwestern Chihuahua. The mountains just east
of the Cascada de Basaseachic in southern Chihuahua form the southeastern point, and the
Sierra de Alamos in southern Sonora marks the
southwestern point. The sky island ranges in Arizona include the Chiricahua, Galiuro, Huachuca,
Pinalefto, Rincon, Santa Catalina, Santa Rita
mountains, and in New Mexico the Animas and
southern Peloncillo mountains. A land of extremes, it is topographically and geologically
complex.
1Dry/ands Institute, Tucson, AZ.
2Desert Legume Program, University' of Arizona, Tucson, AZ.
71
would not be surprising to find the flex and the
two Prunus species in northern Sinaloa. A number
of others occur only in the southern part of our
region and in northern Sinaloa, e.g., Albizia sinaloensis, Brongniartia alamosana, Diospyros
sonorae, Opuntia thurberi var. alamosenses, O.
wilcoxii, Quercus albocincta, Q. tarahumara, and
Sabal uresana. In fact, the flora of northern Sinaloa flora is not separable from that of southern
Sonora and southwestern Chihuahua (Gentry
1946a, 1946b, 1982).
The characters, including size, that constitute
a "tree" are often highly subjective but useful for
indicating trends, and important for considering
keystone or habitat-modifying organisms. The demarcation between the larger shrubs and smaller
trees is especially subjective. We have chosen a
height of 5 m as the artificial limit between shrubs
and trees, and when in doubt have favored including woody plants and excluding the more
herbaceous species with seasonal die-back. We
have also decided that if a plant is classified as a
tree one should be able to climb up into it, or
theoretically climb it if the spines are removed,
without causing it to collapse. Many have a single
trunk at least 10 cm in diameter at about 1 m
above ground level. Some species included in this
listing have multiple trunks arising at or near the
ground and could be classified as shrubs rather
than trees. In some cases a particular species may
be a shrub across most of its distribution in the
region, but in favorable habitats such as moist
tropical canyons it may develop into a sizeable
of the tree flora, or 164 species of southern or
tropical origin reach their northern limits in the
region (Table 1; also see Felger et al., this volume).
Nine plant families represented by trees here do
not extend farther north in western North America,
i.e.,
Bombacaceae,
Clethraceae,
Cochlospermaceae, Erythroxylaceae, Magnoliaceae, Myrsinaceae, Myrtaceae, Olacaceae, and
Opiliaceae.
The total annual precipitation generally decreases from south to north, but increases with
elevation. Precipitation is largely bi-seasonal. The
monsoon-like, summer rainy season is most pronounced and dependable towards the south,
while winter precipitation increases in importance
northward. Soil moisture is the principal limiting
factor in this dry region. The northward expansion of many of the more tropical or subtropical
species is blocked by an invisible "frost-line" of
freezing weather coupled with increasing aridity.
Frosts are infrequent or virtually absent towards
the southern part of the region at lower to intermediate elevations. Increasing aridity northward
tends to raise the lower elevational limits of the
tropical/subtropical trees while the frost-line descends in elevation. This results in narrowing
elevational distributions or bands of tropical/ subtropical species northward and fragmentation of
frost-sensitive and drought-intolerant popUlations
into specific microhabitats. There is often somewhat of a paradox, because microhabitats with the
most favorable moisture conditions (riparian bottomlands and north-facing slopes) tend to
experience the most severe freezing temperatures
(see Burquez et al., in press).
The total flora for the region is estimated to
include at least 4,000 species of vascular plants
(Felger et al., this volume). Within this rich flora
we have documented 233 species of trees (Table
1), which represent about 5 percent of the total
flora. These tree species are distributed in 130
genera and 61 families (Table 2). In our opinion
this tree flora is approximately 95 percent complete, with additional records likely to be found in
the remote mountains and canyons in southwestern Chihuahua and adjacent Sonora. The largest
families of trees are the legume (Fabaceae), oak
(Fagaceae), and pine (Pinaceae) families, and the
most diverse genera are the oaks (Quercus; fig. 1)
and pines (Pinus) (Table 2).
There are about seven tree species and one variety endemic to the region: Fraxinus gooddingii,
flex rubra, Nolina matapensis, Opuntia th urberi
var. thurberi, Prunus gentryi, P. zinggii, Yucca
schottii, and Y. grandiflora (Table 1). However, it
Table 2.-Summary of tree species of the northern Sierra
Madre Occidental and the Sky Islands including the seven
largest families and five largest genera.
Gymnosperms
Dicotyledons
Monocotyledons
Total
Families:
Fabaceae
Fagaceae
Pinaceae
Moraceae
Euphorbiaceae
Cupressaceae
Burseraceae
Salicaceae
Cactaceae
Largest genera:
QuerclJs
Pinus
Bursera
Acacia
Ficus
Juniperus
72
No. of
families
2
No. of
genera
7
56
3
61
119
4
130
23
1
No. of
species
26
198
9
233
36
3
1
2
21
18
9
8
8
8
7
4
6
4
4
7
21
12
8
6
6
5
Figure 1.-leaves of nineteen species of Madrean and sky
island oaks (Quercus): (a) Q. albocincta, cusi, encino
roble, encino prieto, a Red (Black) Oak. (b) Q. arizonica,
Arizona white oak, encino blanco. (c) Q. chihuahuensis,
Chihuahua oak, encino blanco, encino chino, a White
Oak. (d) Q. chryso/epis, canyon live oak, an intermediate
Oak. (e> Q. coccolobifolia, encino negro, a Red Oak. (1)
Q. durifolia, a Red Oak. (g) O. emoryi, Emory oak,
blackjack oak, bel/ota, a Red Oak. (h) O. gambelll,
Gambel oak, Rocky Mountain white oak. (I) Q. gr;sea,
gray oak, a White Oak. (j) 0, hypo/eucoides, silverleaf
oak, encino blanco, encino c%ra do, cusi, a Red Oak.
(k) O. hypo/eucoides, the southern form, sO,metimes
known as Q. scytophylla Liebm. (I) O. mcvaughii, encino
roble, a Red Oak. (m) O. oblongifol/a, Mexican blue oak,
encino azul, a White Oak. en) O. rugosa, net-leaf oak, a
Red Oak. (0) O. sideroxy/a, encino prieto, a Red Oak. (p)
Q. subspathulata, a White Oak. (q)Q. tarahumara, hand
basin oak, encino cajete, a Red Oak. (r) Q. toumeyl, a
White Oak. (s) Q. tubercu/afa, encino amarillo, a White
Oak. (t) Q. vlminea, willow leaf oak, saudllo, a Red Oak.
Drawings by MBJ.
,~.~..v;.~
/
-I:
...J..
J),~.
. . . . .-:.' .. ~
~~~
,\-".'
~
"
.
"
I
I
/'
73
ture used here results from our interpretation of
the taxonomic literature and our work on the flora
of the region. The major vegetation types of the
region and their tree floras are briefly summarized below.
tree (e.g., Aralia humilis and Stemmadenia
tomentosa). Other species are shrubs at higher elevations and in the northern part of the region (due
to repeated freeze-damage or drought-stress) and
trees in the more tropical southern regions (e.g.,
Erythrina flabelliformis, FOllquieria macdougalii,
and Lysiloma watsonil).
The summary of information in Table 1 calls
for some comment. In reality the vegetation is not
as simple as the classification presented. Many
trees may extend into neighboring vegetation
zones along riparian habitats or in other special
situations. Extraordinary "shifts" in vegetation
types occur on limestone (Whitaker & Niering
1965) and hydrothermically altered soils (Goldberg 1982, Burquez et al. 1992). The size-classes in
Table 1 refer to the larger trees within any given
taxon across the entire region. Fire and human
mischief have eliminated most of the largest trees
from many regions. In certain situations many
common trees that are usually small or at most
medium-sized may develop into large trees, e.g.,
Lysiloma watsonii and Vitex mollis along the Rio
Guajaray north of Alamos, and Quercus tarahumara in the vicinity of Mulatos in east-central
Sonora. Perhaps the large number of extraordinarily large trees in the Guarijio Indian region of the
Guajaray is related to local conservation or management practices.
There are, or were, trees virtually everywhere
in the montane areas-most of the region is or
was forested. But man is the enemy vf the tree.
The forests are receding rapidly. Human population in the region remained low and major roads
few until the middle or latter part of the twentieth
century. Much diversity of near natural habitats
remains, but assaults on trees are escalating. Major threats include dams, logging, firewood
cutting, charcoal-making, dearing for agriculture,
mining, urbanization, and replacement of the forests with buffelgrass (Pennisetum ciliare) at lower
elevations in the southern part of the region.
This summary is largely derived from our
study of the trees of Sonora which will be treated
in depth in a forthcoming book (Felger & Johnson
in press). Selected references dealing with trees of
our region or adjacent areas include Benson &
Darrow (1981), Flora North America (1993), Gentry (1942), Hastings et aL (1972), Kearney &
Peebles (1960), Little (1950), Marshall (1957),
Mearns (1907), Pennington & Sarukhan (1968),
Powell (1988), Shreve (1951), Spellenberg et al. (in
prep.), Standley (1920-1926), Steinmann & Felger
(in prep.), Turner et al. (in press), Vines (1960),
Wiggins (1964), and White (1948). The nomencla-
TROPICAL DECIDUOUS FOREST
Tropical deciduous forest (TDF) is characteristic of the dry tropics worldwide. Increase in
human population is leading to global devastation of this habitat. De-forestation and the
resulting desertification has contributed to subtropical belts of misery circling the globe. TDF is
the least studied of the major vegetation types of
the world. Because it is hardly fashionable to save
poorly-known, scrawny and often thorny trees in
hot, uncomfortable climates, world conservation
efforts have largely overlooked TDE The magnificent tropical deciduous forest of the northern
Sierra Madre Occidental is seriously threatened.
The TDF in Sonora and adjacent southwestern
Chihuahua is the dry, northern arm of the great
TDF swath which sweeps northward in western
Mexico. Sonoran-Chihuahuan TDF is sandwiched
between tropical thornscrub at lower elevations to
the west and the oak zone at higher elevations to
the east. Northward, along the east side of the
Sonoran Desert, TDF merges into a kind of inland
subtropical thornscrub (Felger & Lowe 1976, Burquez et al. in press) which in turn merges into
desertscrub (Shreve 1951). Paul Martin and Chuck
Bowden referred to TDF in Sonora as the Secret
Forest (Bowden et al. 1993). Howard Scott Gentry
(1942) called it the Short-tree Forest, and David
Brown (1982) called it Sinaloan Deciduous Forest.
Felger & Lowe (1976) and Burquez et al. (in press)
call it tropical deciduous forest. In its natural condition in Sonora, Chihuahua, and northern
Sinaloa, there is essentially 100 percent ground
cover of forest often 10-15 m tall made up of trees
of tropical affinity.
Summers are long and hot and winters short
and mild. Freezing weather within the forest is
rare and apparently most of the TDF species are
highly frost-sensitive. May and June days grow
hotter and hotter, building up to the beginning of
the long-awaited summer rains. Afternoon douds
increase day by day, and finally, when the violent
thunderstorms begin, the leafless trees and vines
and undergrowth burst forth in a blaze of green
(Gentry 1942). The monsoon rains begin soon after summer solstice, celebrated on June 24 as El
Dia de San Juan. The rains typically continue
through August and into early September. Some
74
trees, such as Bursera spp., Cochlospermum,
Erythrina, Jatropha, Ipomoea, and Pseudobombax, defoliate very soon after the rains cease.
However, most of the trees defoliate more gradually. Midwinter rains may delay leaf-fall of certain
species. Drought-induced deciduating leaves produce a virtually unique but ephemeral display of
highly varied pastel colors (Bowden et aL 1993).
Spring drought brings on final defoliation to most
of the TDF trees. As the weather turns hotter and
dryer from March and April to June, even the tree
chollas (Opuntia thurben) and prickly pears (e.g.,
O. wilcoxiJ) become flaccid and droopy from
water loss. Cicadas call loudly and writers visiting
the Sonoran TDF during the height of the presummer drought tell of skeleton forests and the
lack of greenery. It is awesome to witness the sudden transformation to luxuriant tropical green
with the start of the summer monsoon.
Flowering trees can be found at virtually any
time of the year but there are some significant
peaks of color display. Mid-winter brings the
amapas (Tabebuia spp.), the palo santo (Ipomoea
arborescens), and then the echo (Pachycereus pecten-aboriginum). Later in spring the cuajilote
(Pseudobombax palmen) and rosa amarilla (Cochlospermum vitiiolium) bring forth floral
displays. When fallen leaves are dry and crackling
underfoot in the searing pre-monsoon heat the
hillsides blaze with the dark blue of gauyacan
(Guaiacum coulterl) and rose-purple of nesco
(Lonchocarpus hermannii, = Willardia mexicana).
These are just a few of the more conspicuous flowering trees. By and large the timing of fruit
ripening and seed-fall coincides with the beginning of the summer rains.
Sixty percent (140 species) of the tree species
of the region occur in TDF. Legumes rule the
tropical-derived TDF as well as the regional
thornscrub and Sonoran desertscrub. The
fast-growing mauto (Lysiloma microphyllum) and
many other legumes account for the vast majority
of the TDF vegetative cover. Biological diversity is
high. No single species or small number of species
dominates-the forest is shared by a horde of
species. Prominent arborescent members of TDF
in our region include the following:
• Bursera spp.
• Caesalpinia platyloba
• Ceiba aesculiiolia
• Conzattia m ultif]ora
• Fouquieria macdougalii
• Haematoxylum brasiletto
• Ipomoea arborescens
• Lonchocarpus hermmmii
•
•
•
•
•
•
•
•
•
•
Lysiloma microphyllum
L. TIVatsonii
Pachycereus pecten-aboriginum
Pithecellobium leucospermum
Senna atomaria
Stenocereus montanus
S. thurberi
Tabebuia chrysantha
T. impetiginosa
Wimmeria mexicana
OAK WOODLAND
Oak woodland vegetation is widely
distributed at elevations above desert, grassland,
thornscrub, or tropical deciduous forest, but
below pine-oak woodland or pine forest. The
species composition and tree density in oak
woodland changes both with elevation and
latitude. Although these oak zones have been
called Madrean Evergreen Woodland (Brown
1982), many of the oaks and associated species are
drought-decid uous during the late spring dry
season. Autumn colors associated with falling
leaves in temperate regions are seen in our region
during the pre-summer drought.
Extensive areas in the northern part of the
region are dominated by open woodlands of
Emory oak or bellota (Quercus emorYl). The
acorns are harvested in considerable quantity in
northern Sonora in early summer and sold
locally. This is one of the few remaining
comlnercial, wild food harvests in the region.
The acorns are eaten fresh and are often
consumed in cantinas-the floors becoming
littered with the empty shells. Emory oak,
Mexican blue oak (Q. oblongiiolia), and Arizona
oak ( Q. arizonica) are the most common
low-elevation oaks in the northern part of the
our region. At lower elevations these oak zones
border grassland or desertscrub. There is
sometimes a broad ecotone between oak
woodland and grassland where the oaks become
widely spaced and grasses predominate, Such
areas have been termed oak-grassland or
oak-savanna. In mountains in southeastern and
east-central Sonora oak woodland sometimes
occurs as islands on acidic; hydrothermically·
altered soils within tropical deciduous forest,
The ecotone between these two plant
communities is often only a few meters.
Oak woodland in southeastern Sonora and
southwestern Chihuahua, called Oak Forest by
Gentry (1942), shows considerable tropical
affinity, At its lower limits it borders tropical
75
communities Douglas Fir (Pseudotsuga menziesiJ)
is often locally common in an otherwise pinedominated forest, thus blurring the boundary
with mixed conifer forest.
At higher elevations within the pine-oak zones
the pines become increasingly conspicuous and
the tree density increases so that the vegetation
could be called forest rather than woodland. Pine
forest is characteristically dominated by one species of pine, usually Arizona pine (Pinus
ponderosa var. arizonica), ponderosa pine (P ponderosa var. scopulorum), or white pine (P.
strobi/ormis), with scattered individuals or small
groups of oaks, especially Gambel oak (Q. gambeJiJ) and net-leaf oak (Q. rugosa). Gambel oak is the
only winter-deciduous oak in our region. Pine for ..
est is more widespread in Chihuahua and
Durango than in Sonora. Ponderosa pine replaces
Arizona pine at the higher elevations in Chihuahua and on the northernmost sky islands, These
closely-related pines can be found intermixed in
the Santa Catalina Mountains in southern Arizona. Mountains ranges to the south have only
Arizona pine, while the ranges to the north have
only ponderosa pine.
deciduous forest. Their boundaries are often
remarkably well defined, apparently maintained
by fire. Across the Rio Mayo and Rio Fuerte
mountain drainages it is common to see low fires
creeping almost harmlessly through dry grasses,
forbs, and leaf litter among the barren oaks in
May and June. These fires destroy small TDF trees
and shrubs but not the oaks and their associated
vegetation.
The southern oak woodland is host to a rich
array of subtropical or Mexican oak species. There
is considerable elevational and habitat zonation
among the diverse oaks. Many of the oaks in
southeastern Sonora and nearby southwestern
Chihuahua are strikingly large-leaved (e.g., the
hand-basin oak, Q. tarahumara) as compared to
those of the northern part of the region. The
southern oaks often support tropical epiphytes
such as bromeliads (Tillandsia spp.) and orchids
(e.g., Encyclia microbulbon, LaeJia autumnalis,
and Oncidium cebolleta).
PINE-OAK WOODLAND
Extensive areas of pine-oak woodland occur
along the east side of the continental divide in
western Chihuahua. Along the western slope of
the Sierra Madre Occidental the climate is generally somewhat wetter, with presumably milder
winter temperatures, resulting in a more diverse
flora with more tropical elements .. inel uding
Apache pine (Pinus engelmanmi), Durango pine
(P. durangensis), egg-cone pine (P. oocarpa), pino
chino (P. herrerae), and Mexican tropical-montane
oaks. Towards southeastern Sonora and adjacent
Chihuahua the pine-oak woodland is floristically
and structurally akin to the Mexican pine-oak
woodland of central and southern Mexico.
Pine-oak woodland is continuous with oak
woodland at lower elevations. In pine-oak woodland the pines form the overstory while the oaks
generally form an understory. There are extensive
areas of pine-oak woodland in the mountains of
our region. Pine-oak woodland is included within
the concept of Madrean Evergreen Woodland
(Brown 1982), and the pine forest has been called
Madrean Montane Conifer Forest (Brown 1982).
For our purposes of this study it is not practical to
distinguish pine-oak woodland from pine forest.
Especially in the southern part of our region oaks
are a major part of the forests containing pines.
The abundance of oaks may be in part a consequence of overharvesting of pines. However,
especially in the northern part of the region a distinctive pine forest is distinguishable" In these
MIXED CONIFER FOREST
Mixed conifer forest is restricted to the highest
mountain tops. Winters are cold and summers
cool and moist. It is most extensive in the northern sky islands and at the highest elevations in
Chihuahua. Southward in Sonora, mixed conifer
forest occurs in extremely limited areas on northfacing slopes and riparian canyons on north
slopes. Northeastern Sonora and adjacent Chihuahua support mixed conifer forests at elevations
mostly above 2135 m (7000 ft). Mixed conifer forest barely extends into southeastern Sonora from
Chihuahua above 2100 m (6890 ft) in the upper
reaches of the Rio Mayo Drainage. Because there
are more extensive areas of higher elevation in
Chihuahua the mixed conifer forest is more common there.
Three coniferous genera, Abies (fir), Pinus,
and Pseudotsuga (Douglas fir), define this vegetation. These trees are cOlnmercially valuable for
lumber, Most of the old growth forest has been
logged, but in some places it is recovering from
extensive logging in the mid-twentieth century,
Most of the broadleaf (dieot) trees found here are
winter-deciduous, e.g., Gambel oak (Quercus
gambeJiJ), capulin or wild cherry (Prunus serotina), ash (Fraxinus papillosa), aspen (Populus
tremuloides), and New Mexico locust (Robinia
76
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F. Shreve & I.L. Wiggins. Flora and Vegetation of the SonoranDesert,2vols.Stanford UniversityPress.Stanford.
neomexicana). Riparian canyons are shaded with
tall forests that may include big-tooth maple (Acer
grandidentatum) and alder (Alnus oblongifolia)
sometimes towering to 20 meters or more in
height. The two highest sky island peaks, the Pinalefto and Chiricahua mountains in southeastern
Arizona, support spruce-fir forest (Picea and
Abies) as do a few localities on cold, north-facing
slopes at the highest elevations in southwestern
Chihuahua.
ACKNOWLEDGMENTS
We thank the Wallace Genetic Foundation for
supporting our research on the trees of northwestern Mexico. We also thank Lucinda McDade and
the staff at the University of Arizona Herbarium
for their assistance, and Dennis Breedlove, Alberto Burquez, Mark A. Dinlmitt, Mark Fishbein,
George Ferguson, James Henrickson, Phil Jenkins,
Angelina Martinez-Yrizar, Stephanie Meyer, Andy
Sanders, Richard Spellenberg, Victor Steinmann,
Tom Van Devender, Michael Wilson, David Yetman, and many others for generous help with this
tree flora.
LITERATURE CITED
Benson, L. & R.A. Darrow. 1981. Trees and shrubs of the
Southwestern deserts, 3rd. edition. The University of
Arizona Press, Tucson, A r i z o n a . "
Bowden, C., J.W. Dykinga, & P.S. Martin. 1993. The secret
forest. U ni versity of New Mexico Press. Albuq uerque.
Brown, D.E. (ed.). 1982. Biotic communities of the American Southwest - United States and Mexico. Desert
Plants 4:3-341.
Burquez, A., A. Martlnez-Yrfzar, & R.s. Felger. in press.
Biodiversity at the Southern Desert Edge in Sonora,
Mexico. IN: R. Robichaux, ed. Ecology and Conservation of the Sonoran Desert Flora: a tribute to the desert
laboratory. University of Arizona Press.
Burquez,A.,A.Martinez-Yrizar, &PS.Martin. 1992. From the
high Sierra Madre to the coast: changes in vegetation
along highway 16, Maycobo-Hermosillo. Pp. 239-252. IN:
K.F. Clark, J. Roldan-Quintana, & R. Schmidt (eds.).
Northern Sierra Madre Occidental Province, Mexico,
guidebook. EI Paso Geological Society.EI Paso, TX.
Felger, RS. & C.H. Lowe. 1976. The Island and Coastal
Vegetation and Flora of the Gulf of California, Mexico.
Natural History Museum of Los Angeles County, Contribu tions in Science 285.59 pp .
Felger, R.S. & M.B. Johnson. in press. Trees of Sonora,
Mexico. Oxford University Press. New York.
Flora of North America Editorial Committee .1993. Flora of
North America 2. Oxford U niversi ty Press. New York.
Gentry,H.s.1942. Rio Mayo plants - a study of the flora and
vegetation of the valley of the Rio Mayo, Sonora.
77
Table 1.- Montane tree flora of the northern Sierra Madre Occidental and the Sky Islands.
=
=
Geographic distributions: G
''General'' distributions, found both north and south of the region; T
"Tropical" or "southern" taxa at the
northern limits of their geographic ranges; N
"Northern" taxa at the southern limits of their ranges; R
occuring elsewhere within
approximately the same latitudes as our region; E endemic to our region.
Tree size classes: S
small trees, 5-8 m tall; M
medium-sized trees, 9-18 m; L large trees, 19 or more m.
Habitats: TO tropical deciduous forest; OK oak woodland; PN
pine-oak woodland or forest; MX mixed conifer forest.
Non-native species are Indicated with an asterisk (*).
=
=
=
=
=
=
=
=
G
T
N
R
=
=
E
S
M
L
M
L
L
TO
OK:
PN
MX
GYMNOSPERMS (CONIFERAE - Conifers)
CUPRESSACEAE - CYPRESS FAMILY
Cupressus arizonica Greene
var. arizonica
C. lusitanica Mill.
Juniperus coahuilensis (Martinez) R.P. Adams
J. deppeana Steud.
J. durangensis Martinez
J. flaccida Schldl. var. flaccida
J. scopulorum Sarg.
Taxodium mucronatum Ten.
PINACEAE - PINE FAMILY
Abies bifolia A. Murr.
A. concolor (Gord. & Glend.) Hildebr.
A. durangensis Martinez
Picea chihuahuana Martinez
P. engelmannii Engelm. var. engelmannii
Pinus cembroides Zucco
P. douglasiana Martinez
P. durangensis Martinez
P. edulis Engelm.
P. engelmannii Carr.
P. herrerae Martinez
P. leiophylla Schiede & Deppe var.
chihuahuana (Engelm.) Shaw
P. lumholtzii Robins. & Fern.
P. maximinoi H.E. Moore
P. oocarpa Schiede var. oocarpa
P. ponderosa Laws. & C. Laws. var.
arizonica (Englm.) Shaw
P. ponderosa var. scopulorum Engelm.
P. strobiformis Engelm.
Pseudotsuga menziesii (Mirb.) Franco var.
glauca (Mayr) Franco
G
T
G
G
OK
OK
OK
OK
OK
OK
S
T
T
S
S
S
N
L
T
PN
PN
PN
PN
PN
PN
PN
TD
L
L
L
L
L
N
N
T
T
N
MX
MX
MX
MX
MX
S
T
T
T
L
L
N
S
T
T
L
L
T
T
T
T
L
L
L
L
T
MX
OK
PN
PN
OK
OK
OK
PN
PN
OK
PN
PN
PN
PN
PN
PN
G
L
L
L
PN
PN
PN
MX
MX
MX
G
L
PN
MX
N
MONOCOTYLEDO NS
AGAVACEAE - AGAVE FAMILY
Yucca arizonica McKelv.
Y. grandiflora Gentry
Y. schottii Engelm.
ARECACEAE (PALMAE) - PALM FAMILY
Brahea aculeata (Brandeg.) H.E. Moore
B. dulcis (H.B.K.) Mart.
B. elegans (Becc.) H.E. Moore
B. nitida Andre
Sabal uresana Trel.
N
E
E
T
T
T
T
T
S
S
S
S
NOLINACEAE ~ BEAR-GRASS FAMILY
Nolina matapensis Wiggins
E
OK
OK
OK
PN
TD
TD
TD
TD
TD
OK
OK
PN
TD
OK
S
S
S
(M)
(M)
(M)
M
S
OK
OK
DICOTYLEDONS
ACERACEAE - MAPLE FAMILY
Acer glabrum Torr.
A. grandidentatum Nutt.
A. negundo l.
N
N
N
78
S
L
M
OK
PN
PN
MX
MX
MX
APOCYNACEAE - DOGBANE FAMILY
Plumeria rubra L.
Stemmadenia tomentosa Greenm. var.
palmeri (Rose & StandI.) Woodson
Vallesia glabra (Cav.) Link
T
S
T
T
S
S
TD
(M)
TD
TD
AQUIFOLIACEAE - HOLLY FAMILY
lIex rubra S. Wats.
I. tolucana Hemsl.
T
ARALIACEAE - GINSENG FAMILY
Aralia humilis Cav.
Oreopanax peltatum Linden
T
T
S
S
T
S
TD
T
S
TD
ASTERACEAE (COMPOSITAE) - ASTER
OR COMPOSITE FAMILY
Montanoa rosei Robins. & Greenm.
Parthenium tomentosum DC. var.
stramonium (Greene) Rollins
BETULACEAE - BIRCH FAMILY
Alnus incana (L.) Moench ssp.
tenuifolia (Nutt.) Breit.
A. oblongifolia Torr.
Ostrya virginiana (P. MilL) C. Koch
BIGNONIACEAE - BIGNONIA FAMILY
Chilopsis linearis (Cav.) Sweet ssp.
arcuata (Fosberg) Henricks.
Tabebuia chrysantha (Jacq.) Nichols. ssp. chrysantha
T. impetiginosa (A. DC.) Standi.
BOMBACACEAE - SILK-COTION FAMILY
Celba aesculifolia (H.B.K.) Britt. & Baker
Pseudobombax palmeri (S. Wats.) Dugand
BORAGINACEAE - BORAGE FAMILY
Cordia sonorae Rose
M
M
E
N
N
M
M
T
T
M
M
S
BUDDLEJACEAE - BUTIERFLY-BUSH FAMILY
Buddleja cordata H.B.K. var. cordata
B. parviflora H.B.K.
T
T
S
S
BURSERACEAE - FRANKINCENSE FAMILY
Bursera arborea (Rose) Riley
B. fagaroides (H.B.K.) EngL var. elongata McVaugh
B. grandifolia (SchldL) Engl.
B. lancifolia (Schldl.) Engl.
B. laxiflora S. Wats.
B. penicillata (DC.) Engl.
B. simaruba (L.) Sarg.
B. stenophylla Sprauge & Riley
T
T
T
T
T
T
T
T
CELASTRACEAE - STAFF-TREE FAMILY
Wimmeria mexicana (DC.) Lundell
(L)
(L)
M
M
L
M
N
79
OK
PN
PN
OK
PN
TO
TO
TO
TO
TO
TO
TO
TO
TO
TO
TD
S
S
S
S
(M)
S
S
S
(M)
(M)
TO
TO
TO
TO
S
S
T
TO
TO
(M)
S
S
E
PN
PN
TO
L
TO
MX
MX
OK
TO
TO
S
T
T
T
T
PN
PN
OK
S
N
T
T
T
T
OK
OK
OK
OK
L
L
G
CAPRIFOLIACEAE - HONEYSUCKLE FAMILY
Sambucus mexican a Presl
TD
TD
PN
PN
M
T
CACTACEAE - CACTUS FAMILY
Opuntia thurberi Engelm. var. thurberi
O. thurberi var. alamosenses (Britt. & Rose) Bravo
O. wilcoxii Britt. & Rose
Pachycereus pecten-aboriginum (Engelm.)
Britt. & Rose
Pilosocereus alensis Weber
Stenocereus montanus (Britt. & Rose) Buxb.
S. thurberi (Engelm.) Buxb.
(M)
(M)
OK
MX
MX
MX
CLETHRACEAE - CLETHRA FAMILY
Clethra mexicana DC.
T
M
COCHLOSPERMACEAE - COCHLOSPERMUM FAMILY
Cochlospermum vitifolium (Willd.) K. Spreng.
T
M
TD
CONVOLVULACEAE - MORNING-GLORY FAMILY
Ipomoea arborescens (Humb. & Bonpl.) G. Don
var. pachyleuta Gentry
T
S
(M)
TD
CORNACEAE ~ DOGWOOD FAMILY
Cornus disciflora DC.
T
S
EBENACEAE - PERSIMMON FAMILY
Diospyros sonorae StandI.
T
M
ERICACEAE - HEATH FAMILY
Arbutus arizonica (A. Gray) Sarg.
A. xalapensis Sarg.
T
T
M
M
ERYTHROXYLACEAE - COCA FAMILY
Erythroxylum mexicanum H.B.K.
T
S
T
T
T
T
T
S
EUPHORBIACEAE - SPURGE FAMILY
Croton ct. niveus Jacq.
Drypetes gentryi Monach.
Jatropha cordata (Ort.) Mull. Arg.
Manihot aesculifolia (H.B.K.) Pohl
Manihot sp.
*Ricinus communis L.
Sapium appendiculatum (Mull. Arg.) Pax & K. Hoffm.
Sebastiana pavoniana (Mull. Arg.) Mull. Arg.
OK
(L)
OK
PN
OK
PN
PN
OK
PN
TD
S
S
S
S
S
T
T
(OK)
TD
L
G
PN
M
TD
TD
TD
TD
TD
TD
TD
TD
FABACEAE (LEGUMINOSAE) - LEGUME OR
BEAN FAMILY:
CAESALPINIOIDEAE - SENNA SUBFAMILY
Bauhinia pringlei S. Wats.
Caesalpinia caladenia StandI.
C. palmeri S. Wats.
C. platyloba S. Wats.
Cercidium praecox (Ruiz & Pav.) Harms ssp. praecox
Conzattia multiflora B.L. Robins.
Haematoxylum brasiletto Karst.
*Parkinsonia aculeata L.
Senna atomaria (L.) Irwin & Barneby
MIMOSOIDEAE - MIMOSA SUBFAMILY
Acacia pringlei Rose ssp. californica (Brandeg.) Lee,
Seigler & Ebinger
A. cochliacantha Wi lid .
A. coulteri Benth.
A. farnesiana (L.) Willd.
A. occidentalis Rose
A. pennatula (Cham. & Schldl.) Benth.
Albizia sinaloensis Britt. & Rose
Leucaena lanceolata S. Wats.
*L. leucocephala (Lam.) de Wit
Lysiloma microphyllum Benth.
L. watsonii Rose
Mimosa palmeri Rose
*Pithecellobium dulce (Roxb.) Benth.
P. leucospermum Brandeg.
P. mexicanum Rose
Prosopis glandulosa Torr. var.
torreyana (l.D. Bens.) M.C. Johnst.
P. velutina Woot.
TO
TD
TD
TD
TD
TO
TD
TD
TD
T
T
T
T
T
T
T
T
T
S
S
S
S
S
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
S
S
TD
S
S
TO
TD
TO
L
S
(M)
M
S
TO
M
S
L
M
TO
TO
TO
TO
TO
TO
TO
TO
TO
M
TO
M
S
M
M
(L)
(L)
S
L
S
G
N
80
M
OK
OK
MX
PAPILIONOIOEAE - BEAN SUBFAMILY
Brongniartia alamosana Rydb.
Coursetia glandulosa A. Gray
Oiphysa occidental is Rose
O. suberosa S. Wats.
Erythrina flabelliform is Kearney
Eysenhardtia orthocarpa (A. Gray) S. Wats.
Lonchocarpus hermannii Sousa
Piscidia mollis Rose
Platymiscium trifoliolata Benth.
Robinia neomexicana A. Gray var. neomexicana
FAGACEAE - BEECH FAMILY
Quercus albocincta Trel.
Q. arizonica Sarg.
Q. chihuahuensis Trel.
Q. chrysolepis Liebm.
Q. coccolobifolia Trel.
Q. crassifolia Humb. & Bonpl.
Q. durifolia Seemen
Q. emoryi Torr.
Q. gambelii Nutt
Q. grisea Liebm.
Q. hypoleucoides A. Camus
Q. mcvaughii Spellenb.
Q. oblongifolia Torr.
Q. perpallida Trel.
Q. rugosa Nee
Q. sideroxyla Humb. & Bonpl.
Q. subspathulata Trel.
Q. tarahumara Spellenb. o Bacon & Breedl.
Q. toumeyi Sarg.
Q. tuberculata Liebm.
Q. viminea Trel.
T
T
T
T
T
G
T
T
T
M
M
S
N
T
M
M
M
G
T
N
S
T
T
T
M
M
L
M
M
M
M
M
M
M
M
M
R
N
G
T
R
T
G
T
T
T
JUGLANOACEAE - WALNUT FAMILY
Juglans major (Torr.) Heller
G
OK
PN
OK
OK
OK
OK
OK
OK
OK
OK
PN
PN
PN
OK
OK
OK
OK
OK
OK
OK
(L)
(L)
S
M
M
T
(TO)
(L)
S
S
L
L
MAGNOLIACEAE - MAGNOLIA FAMILY
Magnolia pacifica Vazq. ssp. tarahumara Vazq.
T
L
MALPIGHIACEAE - MALPIGHIA FAMILY
Bunchosia sonorensis Rose
Malpighia umbellata Rose
T
T
S
S
MELIACEAE - CHINABERRY FAMILY
Cedrela odorata L.
Trichilia americana (Ses. & Mog.) T.O. Penn.
T. hirta L.
T
T
T
S
S
TO
TO
TO
TO
T
L
TO
T
T
T
T
T
T
l
l
L
L
L
L
TO
TO
TO
TD
TO
l
TO
81
MX
PN
PN
PN
PN
PN
PN
OK
PN
OK
OK
PN
OK
PN
TO
TO
L
N
PN
PN
OK
T
T
MX
TO
M
T
OK
OK
OK
TD
S
(OK)
OK
MX
PN
PN
PN
PN
PN
PN
LAURACEAE-LAURELFAMILY
Cinnamomum sp.
Persea podadenia Blake
MORACEAE - MULBERRY FAMILY
Chlorophora tinctoria (L.) Benth. & Hook. f.
Ficus cotinifolia H.B.K.
F. insipida Willd.
F. maxima Mill.
F. pertusa L. 1,
F. petiolaris H.B.K.
F. trigonata L.
Morus microphylla Bucki.
Trophis racemosa (L.) Urban
OK
OK
OK
L
N
G
OK
M
T
T
FOUQUIERIACEAE - OCOTILLO FAMILY
Fouquieria macdougalii Nash
F. splendens Engelm. ssp. splendens
TO
TO
TO
TO
TO
TO
TO
TO
TO
S
S
S
S
S
S
S
PN
MYRSINACEAE - MYRSINE FAMILY
Ardisia revoluta H.B.K.
Myrsine coriacea (Sw.) Roem. & Schult.
T
T
MYRTACEAE - MYRTLE FAMILY
*Psidium guajava L.
P. sartorianum (0. Berg) Ndzu.
T
T
S
NYCTAGINACEAE - FOUR-O'CLOCK FAMILY
Pisonia capitata (S. Wats.) StandI.
T
S
OLACACEAE - OLAX FAMILY
Schoepfia schreberi J.F. Gmelin
T
S
OLEACEAE - OLIVE FAMILY
Fraxinus gooddingii Little
F. papillosa Lingelsh.
F. velutina Torr.
PLATANACEAE - PLANE-TREE FAMILY
Platanus wrightii S. Wats.
E
RUTACEAE - RUE FAMILY
*Casimiroa edulis Llave & Lex.
Esenbeckia hartmanii Robins. & Fern.
Ptelea augustifolia Benth.
SALICACEAE - WILLOW FAMILY
Populus angustifolia James
P. brandegeei Schneid.
P. fremontii S. Wats. ssp. fremontii
P. trem uloides Michx.
Salix bondplandiana H.B.K.
S. gooddingii Ball
S. taxifolia H.B.K.
SAPINOACEAE - SOAPBERRY FAMILY
Oodonaea viscosa Jacq.
Sapindus drummondii Hook. & Arn.
S. saponaria L
Thouinia acuminata S. Wats.
T. villosa OC.
(L)
S
L
S
N
E
S
S
T
T
G
L
S
S
S
S
T
T
T
T
G
TD
TO
TO
TO
TO
(M)
R
L
L
L
TO
OK
OK
PN
L
(L)
TO
TO
OK
OK
OK
TO
OK
OK
PN
M
S
N
S
S
(M)
M
T
T
T
S
S
82
MX
OK
M
N
MX
OK
N
G
OK
OK
OK
PN
PN
PN
PN
TO
TO
S
S
N
N
PN
OK
OK
M
R
OK
OK
(M)
S
S
N
PN
TD
E
T
TD
M
M
N
OK
MX
TD
TD
M
N
PN
PN
TD
S
S
S
S
T
T
OK
OK
OK
TD
S
T
T
OK
TD
L
T
PN
TD
G
ROSACEAE - ROSE FAMILY
Prunus emarginata (Dougl.) D. Dietr.
P. gentryi StandI.
P. serotina Ehrh. ssp. capuli (Cav.) McVaugh
P. serotina ssp. virens (Woot. & StandI.) McVaugh
P. zinggii StandI.
Vauquelinia californica (Torr.) Sarg. ssp.
pauciflora (StandI.) Hess & Henricks.
V. californica spp. californica
TD
TD
M
T
RHAMNACEAE - BUCKTHORN FAMILY
Colubrina triflora Brongn.
Karwinskia humboldtiana (Zucc.) Roem. & Schult.
Rhamnus crocea Nutt.
R. cf. mucronata Schldl.
Ziziphus amole (Ses. & Mo~.) M.C. Johnst.
RUBIACEAE - MADDER FAMILY
Cephalanthus salicifolius Humb. & Bonpl.
Hamelia xorullensis H.B.K.
Hintonia latiflora (Ses. & Mo~.) Bullock
Randia echinocarpa Ses. & Mo~.
(M)
G
POLYGONACEAE - BUCKWHEAT FAMILY
Coccoloba goldmanii StandI.
OK
M
R
OPILIACEAE - OPILIA FAMILY
Agonandra racemosa (DC.) StandI.
TD
M
M
TO
TO
TO
PN
MX
SAPOTACEAE - SAPOTE FAMILY
Sideroxylon capiri (OC.) Pitt. ssp.
tempisque (Pitt.) T.O. Penn.
S. lanuginosum Michx. ssp.
rigidum (A. Gray) T.O. Penn.
S. persimile (Hemsl.) T.O. Penn. ssp.
subsessiliflorum (Hemsl.) T.O. Penn.
S. tepicense (StandI.) T.O. Penn.
T
T
SIMAROUBACEAE - SIMAROUBA FAMILY
Alvaradoa amorphoides Liebm.
T
T
SOLANACEAE - NIGHTSHAOE FAMILY
Cestrum lanatum Mart. & Gal.
*Nicotiana glauca Graham
Solanum erianthum O. Oon
N
TILIACEAE - LlNOEN FAMILY
Heliocarpus attenuatus S. Wats.
H. palmeri S. Wats.
Tilia floridana Small
TO
TO
OK
S
TO
OK
S
S
S
TO
TO
TO
OK
OK
M
T
G
T
T
TO
S
S
TO
TO
S
T
T
S
TO
(M)
M
TO
TO
TO
TO
OK
TO
TO
TO
OK
S
URTICACEAE - NETTLE FAMILY
Urera caracasana (Jacq.) Griseb.
T
S
(M)
VERBENACEAE - VERVAIN FAMILY
Lippia umbellata Cav.
Vitex mollis H.B.K.
V. pyramidata Robins.
T
T
T
S
S
S
(M)
ZYGOPHYLLACEAE - CALTROP FAMILY
Guaiacum coulteri A. Gray
T
S
166
PN
L
N
N
22
OK
OK
M
T
32
83
5
8
120
PN
TO
S
G
ULMACEAE - ELM FAMILY
Aphananthe monoica (Hemsl.) Leroy
Celtis iguanea (Jacq.) Sarg.
C. reticulata Torr.
*Ulmus pumila L.
OK
L
L
T
THEOPHRASTACEAE - THEOPHRASTA FAMILY
Jacquinia macrocarpa Cav. ssp. pungens (A. Gray)
Stahl
TO
S
G
STERCULIACEAE - STERCULIA FAMILY
Guazuma ulmifolia Lam.
TAMARICACEAE - TAMARISK FAMILY
*Tamarix ramosissima Ladeb
L
T
(L)
OK
OK
OK
TO
60
54
140
98
75
26