Great Basin Naturalist
Volume 43 Number 4 Article 24
10-31-1983
Range extensions for two dwarf mistletoes (Arceuthobium spp.) in the southwest
Robert L. Mathiasen Northern Arizona University, Flagstaff, Arizona
Kenneth H. Jones New Mexico State University, Sunspot, New Mexico
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Recommended Citation Mathiasen, Robert L. and Jones, Kenneth H. (1983) "Range extensions for two dwarf mistletoes (Arceuthobium spp.) in the southwest," Great Basin Naturalist: Vol. 43 : No. 4 , Article 24. Available at: https://scholarsarchive.byu.edu/gbn/vol43/iss4/24
This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. RANGE EXTENSIONS FOR TWO DWARF MISTLETOES {ARCEUTHOBIUM SPP.) IN THE SOUTHWEST
Robert L. Mathiasen' and Kenneth H. Jones'
Abstract.— A second small population of white fir dwarf mistletoe, Arcetithobimn ahietiniim f. sp. concoloris, is reported from the Santa Catalina Mountains in southern Arizona. The discovery of a second population of this mis-
tletoe in southern Arizona supports the contention that it once had a more southern distribution but has survived past climatic changes in only a few locations in the southwestern United States. The distribution of the Western spnice dwarf mistletoe, Arceuthohium micwcarptim, is extended to the Sacramento Mountains of south central New
Mexico, a range extension of approximately 170 miles. The mistletoe is restricted to an area of about 300 acres, but its potential for further spread is high. The possible implications of this range extension to the biosystematics of Picea spp. and the evolution of A. microcarptim are discussed.
White fir dwarf mistletoe, Arceuthobium This paper reports isolated populations of A. abietinum Engelm. ex Munz f. sp. concoloris abietinum from the Santa Catalina Moun-
Hawksw. & Wiens, is a serious pathogen of tains in south central Arizona and of A. mi- white fir, Abies concolor (Gord. & Glend.) crocarpum from the Sacramento Mountains Lindl., in the western United States (Scharpf in south central New Mexico. 1964, Scharpf and Parmeter 1967). Hawks- In 1979 a very small population of A. worth and Wiens (1972) hst the distribution abietinum was discovered parasitizing white of this dwarf mistletoe from southern Wash- fir in the Santa Catalina Mountains of Pima ington southward through the Cascade Range County, Arizona (Fig. 1). The population oc- and Sierra Nevada to the San Bernardino curs in an area of about 10 acres in Marshall Mountains in southern California, with four Gulch (T. 12 S., R. 16 E., Section 6) near the isolated populations known: the Charleston center of the mountain range at elevations of Mountains and Spring Creek Mountains, Ne- 2,310 to 2,340 m. The predominant tree spe- cies in vada; Kane County in southwestern Utah; the infested stand are white fir, and Grand Canyon National Park, Arizona. Douglas fir (Pseudotsuga menziesii [Mirb.] Franco), and southwestern white pine (Pinus More recently it has been reported from the strobiformis Engelm.). Douglas fir dwarf mis- Chiricahua Mountains of southeastern Ari- tletoe {Arceuthobium douglasii Engelm.) also zona, nearly 300 miles south of the Grand occurs in the stand on Douglas fir. Douglas Canyon populations (Mathiasen 1976). fir dwarf mistletoe has rarely been collected Western spruce dwarf mistletoe, Arceutho- on white fir and can easily be distinguished bium microcarpum (Engelm.) Hawksw. & from white fir dwarf mistletoe using shoot Wiens, severely parasitizes Engelmann and morphology (Hawksworth and Wiens 1972). blue spruce, Picea engelmannii Parry and P. This is the second report of a small, isolated pungens Engelm., in the southwestern United population of A. abietinum from southern States (Hawksworth and Graham 1963, Arizona. The first was reported in the Chiri- Hawksworth and Wiens 1972). In Arizona it cahua Mountains, approximately 100 miles is known from the Kaibab Plateau, the San southeast of the Santa Catalina population Francisco Peaks and Kendrick Peak, the (Mathiasen 1976). The Santa Catalina popu- White Mountains, and the Pinaleno Moun- lation of A. abietinum is nearly 260 miles tains (Hawksworth and Wiens 1972). In New south of the Grand Canyon population of this
Mexico it has only been reported from the taxon, and no other populations of A. abieti- Mogollon Mountains in the west central part num are known between these localities of the state (Hawksworth and Wiens 1972). (Mathiasen 1976).
'School of Forestry, Northern Arizona University, Flagstaff, .\rizona 86011. 'Sacramento Mountain Laboratory, New Mexico State University, Siinspot, New Mexico 88349.
741 742 Great Basin Naturalist Vol. 43, No. 4
Fig. 1. Distribution of Abies concolor and Arcetithobiiim abietiniim (1-4) in Arizona and New Mexico. Numbers 3 and 4 represent the A. abietinitm populations in the Santa Catalina and Chiricahua mountains, respectively.
The discovery of a second population of A. were continuous (Hamilton 1961). However, abietinum in southern Arizona supports the A. abietinum has not been reported from suggestion that A. abietinum had a more Baja California, but may not have survived widespread southern distribution in the past there for the same reasons it has not been re- and only relict populations now exist where ported from more localities in the south- climatic conditions have remained favorable western United States. The discovery of addi- for its survival in the southwestern United tional relict populations of A. abietinum and States (Mathiasen 1976). Both of the southern P. densum subsp. pauciflorum in Mexico or in Arizona populations of A. abietinum occur the mountain ranges with white fir popu- on mesic, north-facing slopes of narrow can- lations between the Grand Canyon and yons at approximately the same elevational southern Arizona would provide more evi- range, and near the lower elevational limits dence concerning the past distribution of of white fir in the Southwest. The occurrence these taxa and their probable migration of an extremely isolated population of the routes into the Southwest. white fir true mistletoe, Phoradendron den- In 1980, a small population of A. micro- sum Torr. ex Trel. subsp. pauciflorum (Torr.) carpum was discovered parasitizing Picea Wiens, parasitizing white fir in the Santa engelmannii in the Sacramento Mountains of Catalina Mountains, may indicate this mis- Otero County, New Mexico (Fig. 2). This tletoe had a more southern past distribution population is approximately 170 miles east also. Phoradendron densum subsp. pauciflo- and slightly south of the nearest known popu- rum has not been found on white fir in other lation of A. microcarpum in the Mogollon mountain ranges in Arizona, but it does occur Mountains of west central New Mexico. Our in the Sierra San Pedro Martir in Baja Cali- surveys over the last two years indicate the fornia, which is farther south than the Santa infestation of A. microcarpum in the Sacra- Catalina populations (Wiens 1964). There- mento Mountains is restricted to three small fore, it may be possible that both of these populations totaling about 300 acres occur- white fir parasites migrated to southern Ari- ring on northern exposures in the general vi- zona along a southern route when Baja Cali- cinity of upper Hay Canyon (T. 17 S., R. 12 fornia and the present mainland of Mexico E., Sections 33-34; T. 18 S. R. 12 E., Sections October 1983 Mathiasen, Jones: Dwarf Mistletoes 743
Fig. 2. Distribution of Picea engehnannii and Arceuthohium microcarpum (1-6) in Arizona and New Mexico. Numbers 5 and 6 represent the A. microcarpum populations in the Pinaleno and Sacramento mountains, respective- ly. Number 7 represents the Chiricahua Mountain population oi Picea engehnannii var. mexicana.
3-4) at elevations ranging from 2,760 to have survived elsewhere in the Sacramento 2,840 m. Our examinations of spruce stands Mountains and in the other mountain ranges in adjacent Spring, Hubbell, Wills, and Sac- with large P. engelmannii populations in ramento canyons have not detected addition- southwestern New Mexico (Little 1971) (Fig. al populations of A. microcarpum. These can- 2). Therefore, the possibility of a more recent yons are similar in elevation and topography introduction of A. microcarpum into the Sac- to Hay Canyon, and their north-facing slopes ramento Mountains would appear more plau- are dominated by a geographically restricted sible than the relict population hypothesis, mixed conifer habitat type {Picea engel- which seems more applicable to the disjunct mannii/Acer glabrum HT) described by Moir populations of A. ahietinum in southern and Ludwig (1979) in which Engelmann Arizona. spruce and Douglas fir are co-dominant over- A more recent introduction of A. micro- story species. In addition, all the areas sur- carpum to the Sacramento Mountains may veyed in the Sacramento Mountains are well then be an example of long-range dis- below the upper elevational limit of 3,100 m semination of a dwarf mistletoe by an avian reported for A. microcarpum (Acciavatti and vector. Hawksworth and Wiens (1972) cite Weiss 1974, Hawksworth and Wiens 1972, examples of dwarf mistletoe distributions that Mathiasen and Hawksworth 1980). There- might be best explained by seed dis- fore, the restriction of A. microcarpum to this semination by avian vectors, and certain in- small an area is anomalous because condi- festation patterns of dwarf mistletoes in con- tions for its spread into adjacent spruce ifer stands are best explained by this means stands appear to be favorable. The apparent also (Hudler et al. 1979). One factor that confinement of this parasite to Hay Canyon must be considered when assessing the possi- may indicate it has arrived relatively recently bilities of long-range dissemination of dwarf in the Sacramento Mountains and did not ac- mistletoes by birds is that Arceuthohium spp. company P. engelmannii at the time of this are dioecious, and a male and female plant tree's migration into this range. Certainly if must become established in an isolated area A. microcarpum had migrated there with P. for a successful infestation to occur. How engelmannii, additional populations should ever, investigations of small satellite dwarf 744 Great Basin Naturalist Vol. 43, No. 4
mistletoe infection centers several meters Arceuthobium microcarpum has not been re- from larger infestations have demonstrated ported on spruce in the Chiricahua Moun- that both male and female plants can become tains (Hawksworth and Wiens 1972), but it is independently established in satellite centers present on P. engelmannii in the Pinaleno (Hudler et al. 1979, Ostry 1978). In addition, Mountains, only 60 miles to the northwest,
Hudler et al. (1979) reported that they be- and is here reported on P. engelmannii from lieve birds are the most likely agents of long- the Sacramento Mountains. Because dwarf distance dispersal of dwarf mistletoes. There- mistletoes are relatively host specific para- fore, the possibility of the establishment of sites, the absence of A. microcarpum from the the Sacramento Mountains population of A. Chiricahua Mountains may be the result of microcarpum by avian vectors should be the close phylogenetic affinities of that considered. spruce population to the Mexican popu- The occurrence of A. microcarpttin in lations of Picea reported by Taylor and Pat- southern New Mexico may be of interest in terson (1980). Hawksworth and Wiens (1972) relation to recent studies of the taxonomic reported that dwarf mistletoes have not been relationships of Picea spp. in the south- found parasitizing Picea chihuahuana Marti- western United States and northern Mexico. nez in northern Mexico and there have been Engelmann spruce populations in the Sacra- no reports of dwarf mistletoes on the Mexi- mento Mountains (32° 48' N), the Pinaleno can populations of P. engelmannii var. mexi- Mountains (32° 30' N), and the Chiricahua cana (Hawksworth, F. C, pers. comm., Mountains (31° 32' N) have been considered 1982). Therefore, these taxa of Picea may as the three most southern populations of this have diverged from their northern relatives species in the United States (Little 1950, to the extent that they are less susceptible or 1971, Daubenmire 1972, Taylor et al. 1975). immune to parasitism by extant species of Ar- However, Taylor and Patterson (1980) have ceuthobium including A. microcarpum. If this shown that the P. engelmannii population is the case, then parasitism of the spruce pop- from the Chiricahua Mountains differs ulations in the Sacramento and Pinaleno slightly morphologically and chemically from mountains would help demonstrate their phy- more northern populations of this taxon and letic affinities to other P. engelmannii popu- that the recently described Picea mexicana lations in the Southwest. The apparent ab-
Martinez (Martinez 1961) is in their opinion sence of A. microcarpum from the Chiricahua not sufficiently different from P. engelmannii Mountains does not indicate conclusively that to warrant separation at the specific level. P. engelmannii var. mexicana is less suscep- Therefore, they have reduced P. mexicana to tible or immune to this mistletoe. Most vari- a variety of P. engelmannii (P. engelmannii etal taxa of principal hosts of dwarf mis- Parry var. mexicana (Martinez) Taylor & Pat- tletoes are susceptible to parasitism when terson) and have included the Chiricahua they occur within the mistletoes' geographic Moimtains population as representative of range (Hawksworth and Wiens 1972), and this combination (Fig. 2). Although Taylor the absence of A. microcarpum from the and Patterson (1980) did not include samples Chiricahua Mountains may simply be a result of the P. engelmannii population from the of its geographic isolation from the spruce Sacramento Mountains in their study, they population there. did sample the P. engelmannii population in Hawksworth and Wiens (1972) suggested the Pinaleno Mountains and concluded it was that A. microcarpum may have had a more representative of P. engelmannii var. engel- northern distribution in the past, but has be- mannii. We consider the spruce populations come isolated as relict endemic populations in the Hay Canyon vicinity to be morpho- near the southern limits of its principal host logically representative of P. engelmannii ranges. They hypothesized that A. micro- var. engelmannii also (Daubenmire 1972, carpum may have evolved in a more northern Jones 1977). In addition, the occurrence of A. area (possibly from the ancestor of A. laricis microcarpum in the Sacramento Mountains or A. tsugense since these taxa resemble A. may have taxonomic significance regarding microcarpum morphologically, our addition), the classification of this spruce population. migrated southward, and become isolated in October 1983 Mathiasen, Jones: Dwarf Mistletoes 745
the Southwest. Recent studies of the dwarf whatever means of dissemination, then, given mistletoe population parasitizing bristlecone enough time, A. microcarpum may eventually pine, Pinus aristata Engelm., as a principal spread into the more northern and southern host on the San Francisco Peaks in north cen- spruce populations of North America. tral Arizona have shown this mistletoe is A. microcarpum (Crawford and Hawksworth 1979, Mathiasen and Hawksworth 1980). Literature Cited However, this population differs morphologi- AcciAVATTi, R. E., AND M. Weiss. 1974. Evaluation of cally and physiologically from other A. mi- J. dwarf mistletoe on Engelmann spruce, Fort crocarpum populations (Mathiasen and Apache Indian Reservation, Arizona. Plant. Dis. Hawksworth 1980), and rarely parasitizes Reptr. 58:418-419. Daubenmire, R. 1972. On the relation between Picea Pinus strobiformis and Abies lasiocarpa var. pungens and Picea engelmannii in the Rocky arizonica (Merriam) Lemm. (Hawksworth Mountains. Rot. 50:733-742. Canadian J. and Wiens 1972, Mathiasen and Hawksworth Hamilton, W. 1961. Origin of the Gulf of California. 1980). Therefore, A. microcarpum may have Geol. Soc. Amer. Bull. 72:1307-1318. Hawksworth, F. G., and D. P. Graham. 1963. Dwarf evolved in the Southwest from an ancestral mistletoes on spruce in the Western United species with a broader host range, including States. Northwest Sci. 37:31-38. species of Pinus and Picea. The A. micro- Hawksworth, F. G., and D. Wiens. 1972. Biology and carpum population parasitizing Pinus aristata classification of dwarf mistletoes (Arceuthobium). U.S. Department of Agriculture, Service, on the San Francisco Peaks would then be an Forest Agricultural Handbook 401. 234 pp. extant population with close phyletic affi- Hudler, G. W., N. Oshima, and F. G. Hawksworth. nities to this hypothesized ancestral species 1979. Bird dissemination of dwarf mistletoe on and may indicate a relatively recent evolu- ponderosa pine in Colorado. Amer. Midi. Nat. 102:27.3-280. tion of A. microcarpum with its radiation and R. 1977. tell Jones, J. How to Engelmann from blue specialization onto P. P. engelmannii and spruce in the Southwest. U.S. Department of Ag- pungens in the southwestern United States. A riculture, Forest Service, Gen. Tech. Rept. RM- more recent evolutionary origin for A. micro- 34. 10 pp. Little, E. L. 1950. Southwestern trees. U.S. Depart- carpum would mean this species may still be ment of Agriculture, Forest Service, Agricultural migrating into areas where spruce popu- Handbook 9. 109 pp. lations are available for colonization. This 1971. Atlas of United States trees. Vol. 1. Con- may better explain its absence from the ex- ifers and important hardwoods. U.S. Department of Agriculture, Forest Service, Misc. Pub. 1146. 9 tensive spruce-fir forests of the central and pp. + illus. northern Rocky Mountains than the hypoth- Martinez, M. 1961. Una nueva especie de Picea en esis of a more northern evolutionary origin Mexico. Anal, del In.st. de Biol. .32:137-142. for A. microcarpum. It seems probable that Mathiasen, R. L. 1976. Southern range extension of the white fir dwarf mistletoe in Arizona. Great Basin A. microcarpum is not restricted to its present Nat. 36:461-462. geographic range by climatic factors or host Mathiasen, R. L., and F. G. Hawksworth. 1980. Tax- susceptibility, it but that evolved and special- onomy and effects of dwarf mistletoe on bristle- ized on Picea shortly before its potential host cone pine on the San Francisco Peaks, Arizona. populations became isolated into small scat- U.S. Department of Agriculture, Forest Service, Res. Pap. RM-224. 10 tered populations in the higher mountain pp. MoiR, W. H., and J. A. Ludwig. 1979. A classification of ranges of the Southwest. At present its fur- spruce-fir and mixed conifer habitat types of Ari- ther migration is severely hampered by its zona and New Mexico. U.S. Department of Agri- short dissemination range and hence its in- culture, Forest Service, Res. Pap. RM-207. 47 pp. ability to spread over the long distances nec- OsTRY, M. E. 1978. Vectors of eastern dwarf mistletoe. Unpubli.shed thesis. Univ. of Minnesota. 141 pp. essary for its migration into the central ScHARPF, R. F. 1964. Dwarf mistletoe on true firs in Cal- Rocky Mountains or into Mexico. However, ifornia. U.S. Department of Agriculture, Forest the Sacramento Mountains population of A. Service, For. Pest Leafl. 89. 7 pp. ScHARPF, R. F., R. 1967. biology microcarpum may indicate that this parasite and J. Parmeter. The and pathology of dwarf mistletoe, Arceuthobium can occasionally make an extremely large ex- campylopodum f. abietinum, parasitizing true firs tension from its otherwise limited distribu- {Abies spp.) in California, U.S. Department of tion. If it is occasionally possible for A. mi- Agriculture, Forest Service, Tech. Bull. 1362. 42 crocarpum to make a large jump, by pp. 746 Great Basin Naturalist Vol. 43, No. 4
S. Williams, R. Daubenmire. 1975. Taylor, R. and T. F. Patterson. 1980. Biosystemat- Taylor, R. J., and J., Interspecific relationships and the question of in- ics of Mexican spruce species and populations, trogression between Picea engelmannii and Picea Taxon 29:421-440. Bot. 53:2547-2555. Wiens, D. 1964. Revisions of the acataphyllous species ptingens. Canadian J. oi Phoradendron. Brittonia 16:11-54.