Index of Species Information

SPECIES:  Acer negundo


SPECIES: Acer negundo
AUTHORSHIP AND CITATION : Rosario, Lynn C. 1988. Acer negundo. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: [].
ABBREVIATION : ACENEG SYNONYMS : NO-ENTRY SCS PLANT CODE : ACNE2 COMMON NAMES : boxelder western boxelder Arizona boxelder California boxelder interior boxelder Texas boxelder violet boxelder TAXONOMY : The fully documented scientific name of boxelder is Acer negundo L. Numerous varieties of this widely distributed species have been designated [16,25,26,41]: Acer negundo var. negundo L., boxelder Acer negundo var. arizonicum Sarg., Arizona boxelder Acer negundo var. californicum Sarg., California boxelder Acer negundo var. interius (Britt.)Sarg., interior boxelder Acer negundo var. texanum Pax., Texas boxelder Acer negundo var. violaceum (Kirchn.) Jaeg., violet boxelder These varieties appear to represent fairly distinct geographic races. Intergradation occurs between varieties and has been considerable between var. violaceum and var. negundo [16]. LIFE FORM : Tree FEDERAL LEGAL STATUS : No special status OTHER STATUS : NO-ENTRY


SPECIES: Acer negundo
GENERAL DISTRIBUTION : Boxelder is widespread in riparian and palustrine communities throughout most of the contiguous United States. Its range extends from New Jersey and central New York west through extreme southern Ontario, central Michigan, northern Minnesota, central Manitoba, central Saskatchewan, southern Alberta and central Montana, eastern Wyoming, Utah, and California; and south to southern Texas and central Florida. It is also local in New Hampshire, Vermont, Massachusetts, Connecticut, Idaho, and Nevada. Boxelder has been naturalized in Maine, southern Quebec, New Brunswick, Nova Scotia, Prince Edward Island, and in southeastern Washington and eastern Oregon. Varieties of boxelder occur in the mountains of Mexico (Nuevo Leon, San Luis Potosi, and south to Chihuahua) and in Guatemala [32]. General distribution by variety is as follows [25]: var. negundo -- eastern United States and introduced to eastern Washington and Oregon var. arizonicum -- Arizona and New Mexico var. californicum -- California var. interius -- Rocky Mountains to Arizona and Canada var. texanum -- western Missouri, eastern Kansas and throughout the Southeast var. violaceum -- northeastern United States and northern Great Plains ECOSYSTEMS : FRES15 Oak - hickory FRES16 Oak - gum - cypress FRES17 Elm - ash - cottonwood FRES18 Maple - beech - birch FRES19 Aspen - birch FRES21 Ponderosa pine FRES28 Western hardwoods FRES29 Sagebrush FRES34 Chaparral - mountain shrub FRES35 Pinyon - juniper FRES36 Mountain grasslands FRES38 Plains grasslands FRES39 Prairie STATES : AL AZ AR CA CO CT DE FL GA ID IL IN IA KS KY LA ME MD MA MI MN MS MO MT NE NV NH NJ NM NC NY ND OH OR PA SC SD TN TX UT VA WA WV WI WY AB MB NS ON PE PQ SK MEXICO BLM PHYSIOGRAPHIC REGIONS : 1 Northern Pacific Border 3 Southern Pacific Border 6 Upper Basin and Range 8 Northern Rocky Mountains 12 Colorado Plateau 13 Rocky Mountain Piedmont 14 Great Plains 15 Black Hills Uplift 16 Upper Missouri Basin and Broken Lands KUCHLER PLANT ASSOCIATIONS : K011 Western ponderosa forest K016 Eastern ponderosa forest K017 Black Hills pine forest K018 Pine - Douglas-fir forest K019 Arizona pine forest K023 Juniper - pinyon woodland K025 Alder - ash forest K033 Chaparral K037 Mountain-mahogany - oak scrub K038 Great Basin sagebrush K055 Sagebrush steppe K056 Wheatgrass - needlegrass shrubsteppe K063 Foothills prairie K064 Grama - needlegrass - wheatgrass K065 Grama - buffalograss K066 Wheatgrass - needlegrass K067 Wheatgrass - bluestem - needlegrass K070 Sandsage - bluestem prairie K074 Bluestem prairie K081 Oak savanna K098 Northern floodplain forest K099 Maple - basswood forest SAF COVER TYPES : 16 Aspen 42 Bur oak 46 Eastern redcedar 61 River birch - sycamore 62 Silver maple - American elm 63 Cottonwood 87 Sweetgum - yellow poplar 93 Sugarberry - American elm - green ash 94 Sycamore - sweetgum - American elm 95 Black willow 109 Hawthorne 235 Cottonwood - willow 236 Bur oak SRM (RANGELAND) COVER TYPES : NO-ENTRY HABITAT TYPES AND PLANT COMMUNITIES : Boxelder is a component of various deciduous forest plant associations in the Great Plains. It is associated with the following overstory dominants: green ash (Fraxinus pennsylvanica), narrowleaf cottonwood (Populus angustifolia), plains cottonwood (P. sargentii), aspen (P. tremuloides), willow (Salix spp.), and bur oak (Quercus macrocarpa). In Arizona and New Mexico, boxelder is the overstory dominant in several high elevation riparian forests. In much of this species' range there are no described plant communities. Published classification schemes listing boxelder as a member of various community types (cts), habitat types (hts), or dominance types (dts) are presented below. Location Classification Authority AZ, NM riparian cts Szaro 1990 MT riparian dts Hansen & others 1988 MT, se ID riparian cts Padgett & others 1989 sw NM riparian hts Medina 1986 sc OK bottomland cts Petranka & Holland 1980 SD,ND: Custer NF general veg. hts Hansen & Hoffman 1988


SPECIES: Acer negundo
WOOD PRODUCTS VALUE : Boxelder is not a desired timber species because its wood is light, soft, close grained, and low in strength [27,41,45]. The wood is used locally for boxes and rough construction [27], and is used occasionally for cheap furniture and woodenware. Boxelder was once used for posts, fencing, and fuel but the soft, spongy wood generally makes poor firewood [40]. IMPORTANCE TO LIVESTOCK AND WILDLIFE : Riparian boxelder communities provide important habitat for many wildlife species and protect livestock from temperature extremes in summer and winter. Many species of birds and squirrels feed on the seeds of boxelder [23,40,46]. Mule deer and white-tailed deer use it in the fall as a browse species of secondary importance [37]. This tree may be poisonous to livestock [9]. PALATABILITY : Palatability of boxelder has been rated as follows [9]: UT WY MT ND Cattle poor poor poor poor Sheep poor poor poor poor Horses poor poor poor poor Elk poor fair ---- ---- Mule deer poor good poor poor White-tailed deer ---- fair poor poor Pronghorn poor poor ---- poor Upland game birds fair fair ---- ---- Waterfowl poor fair ---- ---- Small nongame birds fair fair fair ---- Small mammals fair fair ---- ---- NUTRITIONAL VALUE : The nutritional value of boxelder is low for livestock, with fair energy value, poor protein value, and suspected toxicity [9]. COVER VALUE : Boxelder provides valuable cover for wildlife and livestock, especially in the Great Plains region where quality cover is often lacking. The degree to which this species provides environmental protection during one or more seasons for wildlife species is as follows [9]: UT CO WY MT ND Elk ---- poor ---- poor ---- Mule deer fair ---- good good fair White-tailed deer ---- ---- good good good Pronghorn poor ---- poor ---- poor Upland game birds fair ---- good good ---- Waterfowl poor ---- poor ---- ---- Small nongame birds good good good good ---- Small mammals fair good fair fair ---- VALUE FOR REHABILITATION OF DISTURBED SITES : Growth of boxelder is poor on saline, sodic, sodic-saline, and most acidic soils; it is not recommended for use in rehabilitation of disturbed sites. This tree's potential for erosion control and for long-term revegetation is low to medium [9]. In California, Arizona, and parts of Nevada and New Mexico, boxelder is one of many native species used for revegetating flood control basins to provide quality wildlife habitat [13]. In the southeastern United States where soil moisture (or inundation) is likely to be excessive for several weeks at a time, boxelder is one of the favored flood-tolerant species recommended for recreation plantings. Boxelder is propagated by seed. Guides for seed collection, treatment, and cultivation are available [7,39,44,53]. OTHER USES AND VALUES : Boxelder, first cultivated in 1688 [39], is often held in low regard as an ornamental tree in cities. Its limbs are brittle and break easily; its trunk is susceptible to rot and infested with boxelder bugs, which make their way into houses with the arrival of cold weather. The leaves turn a dull yellow and fall untidily over a long period, as do the winged seeds, giving this species the reputation of being a "dirty tree" [27,31,52]. However, because of its fast growth and drought and cold hardiness, boxelder is popular in rural communities for street and ornamental plantings; and for shelterbelts. Boxelder's abundant sap contains a large proportion of sugar as well as mucilaginous and demulcent properties, and can be made into a pleasant beverage [22]. The Plains Indians used the sap as a source of syrup, and it is still used today, but the product is not as sweet as sugar maple syrup [31]. OTHER MANAGEMENT CONSIDERATIONS : Boxelder is susceptible to mechanical damage by livestock in northern Great Plains wooded draws [4]. This tree is also easily storm damaged; its weak branches often break off in the wind, but the trunk is wind firm [47]. Boxelder is easily injured by heart rot, fire, and insects. It is often infested with boxelder bugs which feed on the tree but rarely kill it [40].


SPECIES: Acer negundo
GENERAL BOTANICAL CHARACTERISTICS : Boxelder is a native deciduous small to large tree with an irregular form. The trunk often divides near the ground into a few long, spreading, rather crooked limbs, which branch irregularly to support a broad, uneven crown. When growing among other trees, boxelder forms a high, open crown, with the undivided portion of the trunk much longer and usually straighter than that of an open-grown tree [27]. This variable-sized tree may reach 70 feet (21 m) in height and 3 feet (0.92 m) in diameter but is more often medium sized, from 40 to 50 feet (12-15 m) high and from 1 to 2 feet (0.3-0.6 m) in diameter [27]. Boxelder may also appear as a large shrub [50], and in upland soil on the Great Plains this tree is usually only about 25 feet (8 m) high with low, crooked branches [45]. Boxelder has a fast growth rate [33,41] and a short life span [46]; it typically lives for 75 years, with 100 years maximum longevity [33]. Growth is rapid when young; long, smooth, green annual shoots extend 2 feet (0.6 m) or more in a year. At maturity growth slows and brittle trunks and limbs shatter; old trunks frequently put out clusters of sprouts and sometimes develop large burls [31]. A drought-tolerant tree once established, boxelder's roots are shallow and spreading, except on deep soils [41,46]. The bark is light grey and smooth but becomes furrowed into narrow, firm ridges and darkens with age. Twigs are stout, light green to purplish or brownish with a polished look or are often covered with a whitish bloom that is easily rubbed off. The blunt buds are 0.125 to 0.25 inch (2-5 mm) long with one or two pairs of scales and are coated with fine white hairs [27]. Boxelder is the only maple with divided leaves. The three to seven leaflets are from 6 to 15 inches (15-38 cm) long, light green above and greyish green below, usually without hairs. The leaflets are shallowly lobed or coarsely toothed [27]. This completely dioecious tree has pale green male and female flowers with a strongly pronounced reduction of flower parts, and contains no rudimentary parts of the opposite sex. Male flowers are on slender stalks in loose clusters, and female flowers are arranged along a separate stem [27,54]. The fruit is composed of two fused, winged samaras which eventually separate upon shedding. The angle separating the two wings is less than 60 degrees [27]. The samaras, about 1.5 inches (4 cm) long, hang in long chains on slender stalks, mature in autumn, and remain on the tree well into the winter [31]. Each contains a single seed without an endosperm [39]. Seeds are 2 to 3 times as long as they are wide and are markedly wrinkled. Many ecotypes of this species occur. Varieties are distinguished by the morphological characteristics of glaucousness, pubescence, or color of the branches and/or samaras. RAUNKIAER LIFE FORM : Phanerophyte REGENERATION PROCESSES : Boxelder reproduces both sexually and asexually [41]. Large seed crops are produced each year [39]. Seeds persist through the winter; they are dispersed by wind or by birds and squirrels [31,51]. Wind will carry these winged seeds up to 100 yards across a snow surface [31]. Boxelder establishes by seed under a wide range of conditions: immediately after disturbance on moist disturbed soil [40], along riverbanks [51], and in areas with heavy cover and medium to heavy competition [28]. In southern Illinois, Hosner and Minckler [28] reported reproduction of boxelder on areas with light, medium, and heavy duff: light duff med duff heavy duff (over 0.5 in) (0.5 to 2 in) (over 2 in) No. of 1- and 2-yr-old seedlings 121 90 35 Vegetative reproduction is also common on damaged plants of this species. New shoots will appear on exposed or injured roots [50]. After the extreme drought condition of the 1930's in the Great Plains, during which nearly all boxelder trees in shelterbelts 30 years or older died back to the ground, many trees recovered by producing root sprouts, forming a dense hedge or undergrowth [1]. In shelterbelts of the northern Great Plains, boxelder has a dense growing habit resulting from the plant suckering at the root collar [13]. Seven years after timber harvest in a South Carolina bottomland, sprouts from boxelder stumps greater than 20 inches (51 cm) in diameter were reported to be dying or losing vigor [38]. Although this species will produce abundant sprouts after disturbance, the primary method of reproduction is through seed, due to the quantity produced each year and the facility of its distribution. SITE CHARACTERISTICS : Boxelder generally grows on moist sites along lakes and streams, on floodplains, and in low-lying wet places where its shallow root system can find abundant moisture [31]. Hardy to extremes of climate [41], boxelder is drought tolerant once well established and can also withstand short periods of flooding [46]. Soils: This species is able to tolerate a wide variety of soils but shows a strong preference for well-drained soils [35]. Although boxelder will grow on soils from gravel to clay, it grows best on deep, sandy loam, loam, or clay loam soils with a medium to rocky texture and a pH of 6.5 to 7.5 [9]. Associates: Throughout its range, boxelder is most often associated with various species of cottonwood (Populus spp.) and willow (Salix spp.). On the northern Great Plains, boxelder will generally outlive cottonwood and willow to become an associate in American elm (Ulmus americana), hackberry (Celtis occidentalis), mulberry (Morus spp.), and green ash communities [2]. In the central Great Plains and in the eastern United States, boxelder occurs with elms (Ulmus spp.), sugar maple (Acer rubrum), basswood (Tilia spp.), and ashes (Fraxinus spp.), which eventually replace boxelder in the overstory along with other more durable and shade-tolerant species [31,51]. At higher elevations on the Utah plateaus, boxelder occurs in the riparian zone with water birch (Betula occidentalis), narrowleaf cottonwood (Populus angustifolia), willows, and blue spruce (Picea pungens) [31]. In New Mexico and Arizona, scattered along streambeds in riparian forests at higher elevations, boxelder is a typical canopy dominant with Arizona alder (Alnus oblongifolia) and coyote willow (Salix exigua) [35]. Elevation: The elevational ranges for boxelder in several states are as follows [9,29,31,35,36,46]: AZ from 4,450 to 8,000 feet (1,356-2,438 m) CO 4,500 to 7,870 feet (1,372-2,400 m) MT 2,240 to 4,500 feet (680-1,372 m) NE 2,600 to 4,500 feet (792-1,372 m) NM 6,350 to 6,775 feet (1,935-2,065 m) ND 2,310 to 3,840 feet (704-1,170 m) SD 3,000 to 3,500 feet (914-1,067 m) UT 4,000 to 10,000 feet (1,219-3,048 m) WY 3,500 to 7,700 feet (1,067-2,347 m) Mexico 4,600 to 5,947 feet (1,400-1,800 m) SUCCESSIONAL STATUS : Boxelder occurs in a variety of forest types ranging from early to late seral, making its successional position difficult to determine. It is moderately shade tolerant but does not reproduce in its own shade. It usually establishes under pioneering species such as cottonwood and willow, particularly in the northern Great Plains [2], and is then followed by more shade-tolerant, climax species [40]. In Arizona and New Mexico, boxelder is a dominant or codominant overstory species in several high-elevation riparian communities [48]. SEASONAL DEVELOPMENT : Boxelder flowers from March through May with or before the appearance of the leaves. The fruit, a winged samara, ripens from September through October and is dispersed from September through March [39,50,53]. Boxelder's leaves turn a dull yellow color in the autumn and drop throughout the fall and winter [40].


SPECIES: Acer negundo
FIRE ECOLOGY OR ADAPTATIONS : Boxelder grows on moist bottomland sites which are seldom subject to burning. This thin-barked species is injured by fire [50], but how it regenerates following fire is not known. Boxelder produces large yearly crops of wind-dispersed seeds which germinate on a wide variety of soils; this is most likely boxelder's primary fire survival strategy. This tree also sprouts from the exposed roots, root crown, or stump following top-killing mechanical damage [1,13,19,38], and it is likely that boxelder would sprout following fire severe enough to girdle or top-kill the adult tree. FIRE REGIMES : Find fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find Fire Regimes". POSTFIRE REGENERATION STRATEGY : off-site colonizer species; seed transported by wind;postfire years 1&2 off-site colonizer species; seed transported by animals;post-fire years 1&2 survivor species; on-site surviving root crown or caudex (possible)


SPECIES: Acer negundo
IMMEDIATE FIRE EFFECT ON PLANT : Van Dersal reports that this thin-barked species is injured by fire [50]. DISCUSSION AND QUALIFICATION OF FIRE EFFECT : NO-ENTRY PLANT RESPONSE TO FIRE : Boxelder most likely reestablishes following fire via wind-dispersed seeds [31,51]. It may also sprout from the roots, the root collar, or stump if girdled or top-killed by fire. DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : The Research Project Summary Effects of surface fires in a mixed red and eastern white pine stand in Michigan provides information on prescribed fire and postfire response of plant community species, including boxelder, that was not available when this species review was written. FIRE MANAGEMENT CONSIDERATIONS : NO-ENTRY


SPECIES: Acer negundo
REFERENCES : 1. Albertson, F. W.; Weaver, J. E. 1945. Injury and death or recovery of trees in prairie climate. Ecological Monographs. 15: 393-433. [4328] 2. Bellah, R. Glenn; Hulbert, Lloyd C. 1974. Forest succession on the Republican River floodplain in Clay County, Kansas. Southwestern Naturalist. 19(2): 155-166. [241] 3. Bernard, Stephen R.; Brown, Kenneth F. 1977. Distribution of mammals, reptiles, and amphibians by BLM physiographic regions and A.W. Kuchler's associations for the eleven western states. Tech. Note 301. Denver, CO: U.S. Department of the Interior, Bureau of Land Management. 169 p. [434] 4. Butler, Jack; Goetz, Harold. 1984. Influence of livestock on the composition and structure of green ash communities in the Northern Great Plains. In: Noble, Daniel L.; Winokur, Robert P., eds. Wooded draws: characteristics and values for the Northern Great Plains: Symposium proceedings; 1984 June 12-13; Rapid City, SD. Great Plains Agricultural Council Publication No. 111. Rapid City, SD: South Dakota School of Mines and Technology, Biology Department: 44-49. [572] 5. Byrd, Nathan A. 1978. Some effects of soil moisture on management of forest cover for recreation and aesthetics. In: Balmer, William E., ed. Proceedings--soil productivity symposium; 1977 November 1-3; Myrtle Beach, SC. Atlanta, GA: U.S. Department of Agriculture, Forest Service, Southeastern Area, State and Private Forestry: 119-124. [4263] 6. Correll, Donovan S.; Johnston, Marshall C. 1970. Manual of the vascular plants of Texas. Renner, TX: Texas Research Foundation. 1881 p. [4003] 7. Cram, W. H. 1983. Maturity and viability of boxelder maple seeds. Tree Planter's Notes. 34(2): 36-37. [5007] 8. Demos, E. K.; Peterson, P.; Williams, G. J., III. 1973. Frost tolerance among populations of Acer negundo L. American Midland Naturalist. 89(1): 223-228. [2695] 9. Dittberner, Phillip L.; Olson, Michael R. 1983. The plant information network (PIN) data base: Colorado, Montana, North Dakota, Utah, and Wyoming. FWS/OBS-83/86. Washington, DC: U.S. Department of the Interior, Fish and Wildlife Service. 786 p. [806] 10. Eyre, F. H., ed. 1980. Forest cover types of the United States and Canada. Washington, DC: Society of American Foresters. 148 p. [905] 11. Garrison, George A.; Bjugstad, Ardell J.; Duncan, Don A.; [and others]. 1977. Vegetation and environmental features of forest and range ecosystems. Agric. Handb. 475. Washington, DC: U.S. Department of Agriculture, Forest Service. 68 p. [998] 12. George, Ernest J. 1953. Tree and shrub species for the Northern Great Plains. Circular No. 912. Washington, DC: U.S. Department of Agriculture. 46 p. [4566] 13. George, Ernest J. 1953. Thirty-one-year results in growing shelterbelts on the Northern Great Plains. Circular No. 924. Washington, DC: U.S. Department of Agriculture. 57 p. [4567] 14. Girard, Michele Marie. 1985. Native woodland ecology and habitat classification of southwestern North Dakota. Fargo, ND: North Dakota State University. 314 p. Dissertation. [1025] 15. Granholm, Stephen L.; Henry, William P.; Kanemoto, William D.; Palmer, Rexford E. 1988. Designing riparian plantings to mimic native forests within four hydrologic zones along the Sacramento River. In: Rieger, John P.; Williams, Bradford K., eds. Proceedings of the second native plant revegetation symposium; 1987 April 15-18; San Diego, CA. Madison, WI: University of Wisconsin - Arboretum, Society of Ecological Restoration & Management: 198-212. [4115] 16. Great Plains Flora Association. 1986. Flora of the Great Plains. Lawrence, KS: University Press of Kansas. 1392 p. [1603] 17. Griffin, James R.; Critchfield, William B. 1972. The distribution of forest trees in California. Res. Pap. PSW-82. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station. 118 p. [1041] 18. Habeck, James R. 1987. Present-day vegetation in the northern Rocky Mountains. In: Contributions to a symposium on the evolution of the modern flora of the northern Rocky Mountains. Annals of the Missouri Botanical Garden. 74(4): 804-840. [3971] 19. Hansen, Paul L.; Hoffman, George R. 1988. The vegetation of the Grand River/Cedar River, Sioux, and Ashland Districts of the Custer National Forest: a habitat type classification. Gen. Tech. Rep. RM-157. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 68 p. [771] 20. Hansen, Paul L.; Hoffman, George R.; Steinauer, Gerry A. 1984. Upland forest and woodland habitat types of the Missouri Plateau, Great Plains Province. In: Noble, Daniel L.; Winokur, Robert P., eds. Wooded draws: characteristics and values for the Northern Great Plains: Symposium proceedings; 1984 June 12-13; Rapid City, SD. Great Plains Agricultural Council Publ. No. 111. Rapid City, SD: South Dakota School of Mines and Technology, Biology Department: 15-26. [1078] 21. Harlacher, Richard A. 1987. Determination of planting densities for revegetation projects. In: Rieger, John P.; Williams, Bradford K., eds. Proceedings of the second native plant revegetation symposium; 1987 April 15-18; San Diego, CA. Madison, WI: University of Wisconsin Arboretum, Society for Ecological Restoration & Management: 22-27. [4090] 22. Havard, V. 1885. Report on the flora of western and southern Texas. Proceedings of the United States National Museum. 8(29): 449-533. [5067] 23. Hehnke, Merlin; Stone, Charles P. 1979. Value of riparian vegetation to avian populations along the Sacramento River Sy. In: Johnson, R. Roy; McCormick, J. Frank, technical coordinators. Strategies for protection and management of floodplain wetlands & other riparian ecosystems: Proc. of the symposium; 1978 December 11-13; Callaway Gardens, GA. General Technical Report WO-12. Washington, DC: U.S. Department of Agriculture, Forest Service: 228-235. [4363] 24. Heinselman, Miron L. 1981. Fire intensity and frequency as factors in the distribution and structure of northern ecosystems. In: Mooney, H. A.; Bonnicksen, T. M.; Christensen, N. L.; [and others], technical coordinators. Fire regimes and ecosystem properties: Proceedings of the conference; 1978 December 11-15; Honolulu, HI. Gen. Tech. Rep. WO-26. Washington, DC: U.S. Department of Agriculture, Forest Service: 7-57. [4390] 25. Hitchcock, C. Leo; Cronquist, Arthur. 1961. Vascular plants of the Pacific Northwest. Part 3: Saxifragaceae to Ericaceae. Seattle, WA: University of Washington Press. 614 p. [1167] 26. Holmgren, Arthur H.; Reveal, James L. 1966. Checklist of the vascular plants of the Intermountain Region. Res. Pap. INT-32. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station. 160 p. [1184] 27. Hosie, R. C. 1969. Native trees of Canada. 7th ed. Ottawa, ON: Canadian Forestry Service, Department of Fisheries and Forestry. 380 p. [3375] 28. Hosner, John F.; Minckler, L. S. 1960. Hardwood reproduction in the river bottoms of southern Illinois. Forest Science. 6(1): 67-77. [3738] 29. Johnston, Barry C. 1987. Plant associations of Region Two: Potential plant communities of Wyoming, South Dakota, Nebraska, Colorado, and Kansas. 4th ed. R2-ECOL-87-2. Lakewood, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Region. 429 p. [3519] 30. Kuchler, A. W. 1964. Manual to accompany the map of potential vegetation of the conterminous United States. Special Publication No. 36. New York: American Geographical Society. 77 p. [1384] 31. Lanner, Ronald M. 1983. Trees of the Great Basin: A natural history. Reno, NV: University of Nevada Press. 215 p. [1401] 32. Little, Elbert L., Jr. 1979. Checklist of United States trees (native and naturalized). Agric. Handb. 541. Washington, DC: U.S. Department of Agriculture, Forest Service. 375 p. [2952] 33. Loehle, Craig. 1988. Tree life history strategies: the role of defenses. Canadian Journal of Forest Research. 18(2): 209-222. [4421] 34. Lyon, L. Jack; Stickney, Peter F. 1976. Early vegetal succession following large northern Rocky Mountain wildfires. In: Proceedings, Tall Timbers fire ecology conference and Intermountain Fire Research Council fire and land management symposium; 1974 October 8-10; Missoula, MT. No. 14. Tallahassee, FL: Tall Timbers Research Station: 355-373. [1496] 35. Medina, Alvin L. 1986. Riparian plant communities of the Fort Bayard watershed in southwestern New Mexico. Southwestern Naturalist. 31(3): 345-359. [1629] 36. Minckley, W. L.; Brown, David E. 1982. Wetlands. In: Brown, David E., ed. Biotic communities of the American Southwest--United States and Mexico. Desert Plants. 4(1-4): 223-287. [8898] 37. Nelson, Jack Raymond. 1961. Composition and structure of the principal woody vegetation types in the North Dakota Badlands. Fargo, ND: North Dakota State University. 195 p. Thesis. [161] 38. Nix, L. E.; Cox, S. K. 1987. Cherrybark oak enrichment plantings appear successful after seven years in South Carolina bottomlands. In: Phillips, Douglas R., compiler. Proceedings of the fourth biennial southern silvicultural research conference; 1986 November 4-6; Atlanta, GA. General Technical Report SE-42. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southeastern Forest Experiment Station: 129-132. [4197] 39. Olson, David F., Jr.; Gabriel, W. J. 1974. Acer L. maple. In: Schopmeyer, C. S., technical coordinator. Seeds of woody plants in the United States. Agric. Handb. 450. Washington, DC: U.S. Department of Agriculture, Forest Service: 187-194. [7462] 40. Patterson, Rich. 1985. The humblest maple. American Forests. 91(5): 46-48. [5005] 41. Preston, Richard J., Jr. 1948. North American trees. Ames, IA: The Iowa State College Press. 371 p. [1913] 42. Raunkiaer, C. 1934. The life forms of plants and statistical plant geography. Oxford: Clarendon Press. 632 p. [2843] 43. Read, Ralph A. 1964. Tree windbreaks for the Central Great Plains. Agric. Handb. 250. Washington, DC: U.S. Department of Agriculture, Forest Service. 68 p. [2897] 44. Roe, Eugene I. 1941. Effect of temperature on seed germination. Journal of Forestry. 39: 413-414. [2019] 45. Stephens, H. A. 1973. Woody plants of the North Central Plains. Lawrence, KS: The University Press of Kansas. 530 p. [3804] 46. Sutton, Richard F.; Johnson, Craig W. 1974. Landscape plants from Utah's mountains. EC-368. Logan, UT: Utah State University, Cooperative Extension Service. 135 p. [49] 47. Szaro, Robert C. 1989. Riparian forest and scrubland community types of Arizona and New Mexico. Desert Plants. 9(3-4): 70-138. [604] 48. Szaro, Robert C.; Patton, David R. 1986. Riparian habitat classification in the southwestern United States. Transactions of the 51st North American Wildlife and Natural Resources Conference: 215-221. [3516] 49. U.S. Department of Agriculture, Soil Conservation Service. 1982. National list of scientific plant names. Vol. 1. List of plant names. SCS-TP-159. Washington, DC. 416 p. [11573] 50. Van Dersal, William R. 1938. Native woody plants of the United States, their erosion-control and wildlife values. Washington, DC: U.S. Department of Agriculture. 362 p. [4240] 51. Weaver, J. E. 1960. Flood plain vegetation of the central Missouri Valley and contacts of woodland with prairie. Ecological Monographs. 30(1): 37-64. [275] 52. Welsh, Stanley L.; Atwood, N. Duane; Goodrich, Sherel; Higgins, Larry C., eds. 1987. A Utah flora. Great Basin Naturalist Memoir No. 9. Provo, UT: Brigham Young University. 894 p. [2944] 53. Williams, Robert D.; Hanks, Sidney H. 1976. Hardwood nurseryman's guide. Agric. Handb. 473. Washington, DC: U.S. Department of Agriculture, Forest Service. 78 p. [4182] 54. Wright, Jonathan W. 1953. Notes on flowering and fruiting of northeastern trees. Station Paper No. 60. Upper Darby, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 38 p. [5009]